以查询部门表为例
部门表sql语句
/*
Navicat MySQL Data Transfer
Source Server : a
Source Server Version : 50027
Source Host : localhost:3306
Source Database : erp
Target Server Type : MYSQL
Target Server Version : 50027
File Encoding : 65001
Date: 2017-12-24 12:04:04
*/
SET FOREIGN_KEY_CHECKS=0;
-- ----------------------------
-- Table structure for `deptment`
-- ----------------------------
DROP TABLE IF EXISTS `deptment`;
CREATE TABLE `deptment` (
`deptId` int(11) NOT NULL auto_increment,
`deptName` varchar(50) NOT NULL,
`discrbe` varchar(200) default NULL,
PRIMARY KEY (`deptId`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of deptment
-- ----------------------------
INSERT INTO deptment VALUES ('1', '技术部', '湖南');
INSERT INTO deptment VALUES ('3', '行政部', '湖南衡阳');
INSERT INTO deptment VALUES ('4', '市场部', '湖南');
-- ----------------------------
-- Table structure for `employee`
-- ----------------------------
DROP TABLE IF EXISTS `employee`;
CREATE TABLE `employee` (
`eid` int(11) NOT NULL auto_increment,
`ename` varchar(50) NOT NULL,
`esex` char(2) default NULL,
`ebirthday` date default NULL,
`ejiondate` date default NULL,
`username` varchar(50) NOT NULL,
`pwd` varchar(50) NOT NULL,
`deptid` int(11) NOT NULL,
`eno` varchar(50) NOT NULL,
PRIMARY KEY (`eid`),
KEY `deptid` (`deptid`),
CONSTRAINT `deptid` FOREIGN KEY (`deptid`) REFERENCES `deptment` (`deptId`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of employee
-- ----------------------------
INSERT INTO employee VALUES ('1', 'zhangsan', '女', '2017-12-24', '2017-12-24', 'zhangsan', 'aaaaa', '1', 'YC1002');
INSERT INTO employee VALUES ('2', 'lisi', '男', '2017-12-24', '2017-12-24', 'lisi', 'aaaaa', '1', 'YC1003');
INSERT INTO employee VALUES ('3', 'lydia', '女', '2017-12-24', '2017-12-24', 'lydia', 'aaaaa', '1', 'YC1001');
思路
1.调用dbHelper中的方法
自定义Mybatis:
MybatisConfig:解析配置文件
数据源配置信息：
url
driver
username
password
DataSource 数据源对象存储配置信息
映射文件 ： XXMapper.xml
List<String> mappers;
SqlSessionFactory
解析XXMapper.xml 文件
id
resultType
paramtertype
sql
MapperInfo 存储每个映射语句 ---》Map
SqlSession
getDataSource() -->DbHelper--->设置 getConn( )
selectOne()
dbHelper.find()
selectList()
所需建的包和文件
mybatis-config.xml
<?xml version="1.0" encoding="UTF-8" ?>
<config>
<dataSource>
<property name="driver" value="com.mysql.jdbc.Driver"></property>
<property name="url" value="jdbc:mysql://localhost:3306/mybatis2"></property>
<property name="username" value="root"></property>
<property name="password" value="admin"></property>
</dataSource>
<mappers>
<mapper resource="cn/itcast/dao/Deptment.xml"></mapper>
</mappers>
</config>Deptment.xml
<!-- namespace：命名空间，用于隔离sql，还有一个很重要的作用，后面会讲 -->
<!-- sql语句 -->
<mapper>
<select id="get" resultType="cn.itcast.bean.DeptmentBean">
select * from deptment
</select>
</mapper>DeptmentBean.java
package cn.itcast.bean;
import java.io.Serializable;
import java.util.List;
public class DeptmentBean implements Serializable{
/**
*
*/
private static final long serialVersionUID = 1L;
private Integer deptId;
private String deptName;
private String discrbe;
public DeptmentBean() {
}
public DeptmentBean(Integer deptId, String deptName, String discrbe) {
this.deptId = deptId;
this.deptName = deptName;
this.discrbe = discrbe;
}
public Integer getDeptId() {
return deptId;
}
public void setDeptId(Integer deptId) {
this.deptId = deptId;
}
public String getDeptName() {
return deptName;
}
public void setDeptName(String deptName) {
this.deptName = deptName;
}
public String getDiscrbe() {
return discrbe;
}
public void setDiscrbe(String discrbe) {
this.discrbe = discrbe;
}
@Override
public String toString() {
return "DeptmentBean [deptId=" + deptId + ", deptName=" + deptName + ", discrbe=" + discrbe + "]";
}
}
DataSource.java
package cn.itcast.mybatis;
public class DataSource {
private String url;
private String driverClassName;
private String user;
private String password;
public String getUrl() {
return url;
}
public void setUrl(String url) {
this.url = url;
}
public String getDriverClassName() {
return driverClassName;
}
public void setDriverClassName(String driverClassName) {
this.driverClassName = driverClassName;
}
public String getUser() {
return user;
}
public void setUser(String user) {
this.user = user;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
DBHelper.java
package cn.itcast.mybatis;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Method;
import java.sql.Blob;
import java.sql.Clob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
public class DBHelper {
private DataSource dataSource;
public DBHelper(DataSource dataSource){
this.dataSource = dataSource;
try {
Class.forName(dataSource.getDriverClassName());
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
static{
// try {
// Class.forName(ReaderPro.getReaderPro().getProperty("driverClassName"));
// } catch (ClassNotFoundException e) {
// e.printStackTrace();
// }
}
/**
* 获取连接的方法
* @return
*/
private Connection getConnection(){
Connection cn = null;
try {
//cn = DriverManager.getConnection(ReaderPro.getReaderPro().getProperty("url"),ReaderPro.getReaderPro());
cn = DriverManager.getConnection(dataSource.getUrl(), dataSource.getUser(), dataSource.getPassword());
//cn = DriverManager.getConnection("", dataSource.getUser(), dataSource.getPassword());
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return cn;
}
/**
* 给预编译语句中的占位符赋值
* @param pstmt 要赋值的预编译语句块
* @param params 对应的占位符?的值
*/
private void setParams(PreparedStatement pstmt,Object ... params){
//给预编译执行语句中的占位符赋值
if(params!=null && params.length>0){ //说明要执行的sql语句中有占位符?
for(int i=0,len=params.length;i<len;i++){
try {
pstmt.setObject(i+1,params[i]);
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
/**
* 给预编译语句中的占位符赋值
* @param pstmt 要赋值的预编译语句块
* @param params 对应的占位符?的值
*/
private void setParams(PreparedStatement pstmt,List<Object> params){
//给预编译执行语句中的占位符赋值
if(params!=null && params.size()>0){ //说明要执行的sql语句中有占位符?
for(int i=0,len=params.size();i<len;i++){
try {
pstmt.setObject(i+1,params.get(i));
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
/**
* 给预编译语句中的占位符赋值
* @param pstmt 要赋值的预编译语句块
* @param params 对应的占位符?的值
*/
private void setParams(PreparedStatement pstmt,String ... params){
//给预编译执行语句中的占位符赋值
if(params!=null && params.length>0){ //说明要执行的sql语句中有占位符?
for(int i=0,len=params.length;i<len;i++){
try {
pstmt.setString(i+1,params[i]);
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
/**
* 关闭资源的方法
* @param rs 要关闭的结果集
* @param pstmt 要关闭的预编译语句
* @param con 要关闭的连接
*/
private void closeAll(ResultSet rs,PreparedStatement pstmt,Connection con){
if(rs!=null){
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(pstmt!=null){
try {
pstmt.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(con!=null){
try {
con.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
/**
* 执行更新操作
* @param sql 要执行更新的sql语句（insert、delete、update）
* @param params 要执行的更新语句中占位符?的值，给定的顺序必须跟?的顺序一致
* @return 更新语句执行后，所影响的数据的行数
*/
public int update(String sql,String ... params){
Connection con=null;
PreparedStatement pstmt=null;
int result=0;
try {
con=this.getConnection(); //获取连接
//创建预编译执行语句
pstmt=con.prepareStatement(sql);
this.setParams(pstmt, params);
//执行预编译语句，获取结果
result=pstmt.executeUpdate();
} catch (SQLException e) {
e.printStackTrace();
} finally{
this.closeAll(null, pstmt, con);
}
return result;
}
/**
* 查询数据
* @param sql 要执行的查询语句
* @param params 查询语句中占位符?对应值
* @return 返回满足条件的所有数据
*/
public List<Map<String,Object>> finds(String sql,Object ... params){
Connection con=null;
PreparedStatement pstmt=null;
ResultSet rs=null;
List<Map<String,Object>> list=new ArrayList<Map<String,Object>>();
int pp = 0;
try {
con=this.getConnection(); //获取连接
pstmt=con.prepareStatement(sql); //创建预编译执行语句
this.setParams(pstmt, params); //给预编译执行语句中的占位符赋值
rs=pstmt.executeQuery(); //执行预编译语句获取结果集
rs = pstmt.executeQuery();
ResultSetMetaData rsmd=rs.getMetaData(); //获取结果集中列的信息
int colCount=rsmd.getColumnCount(); //获取结果集中列的数量
String[] colNames=new String[colCount];
for(int i=0;i<colCount;i++){ //通过列的索引循环获取每个列的列名
colNames[i]=rsmd.getColumnName(i+1).toLowerCase();
}
Map<String,Object> map=null; //每一个map中存放一行数据
//通过列名循环获取每个列的值
Blob blob;
Object obj=null;
String typeName=null;
byte[] bt=null;
InputStream is=null;
while(rs.next()){ //每循环一次就是一行数据
pp++;
map=new HashMap<String,Object>();
for(String colName:colNames){ //循环着一行中的每个列，通过每个列的列名获取这个列的值
obj=rs.getObject(colName);
if(obj!=null){
typeName=obj.getClass().getSimpleName();
if("BLOB".equals(typeName)){
try {
blob=(Blob)obj;
bt=new byte[ (int) blob.length() ];
is=blob.getBinaryStream();
is.read(bt);
} catch (IOException e) {
e.printStackTrace();
} finally{
if(is!=null){
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
map.put(colName,bt); //以列名为键，以对应列的值为值
}else{
map.put(colName,obj); //以列名为键，以对应列的值为值
}
}else{
map.put(colName,obj); //以列名为键，以对应列的值为值
}
}
list.add(map);
}
} catch (SQLException e) {
e.printStackTrace();
} finally{
this.closeAll(rs, pstmt, con);
}
return list;
}
public List<String> getAllColnumsName(ResultSet rs) throws Exception{
List<String> list = new ArrayList<String>();
ResultSetMetaData rsmd = rs.getMetaData(); //获取结果集中列的信息
int colCount=rsmd.getColumnCount(); //获取结果集中列的数量
for(int i=0;i<colCount;i++){ //通过列的索引循环获取每个列的列名
String x = rsmd.getColumnName(i+1).toLowerCase();
list.add(x);
}
return list;
}
/**
* 获取多行值
* @param sql
* @param params
* @param c
* @return
*/
public <T> List<T> findAll(String sql,List<Object> params,Class c){
List<T> list = new ArrayList<T>();
Connection con=null;
PreparedStatement pstmt=null;
ResultSet rs=null;
try{
con = this.getConnection();
pstmt = con.prepareStatement(sql);
//设置参数
this.setParams(pstmt, params);
//执行
rs = pstmt.executeQuery();
//获取所有的列名
List<String> columnNames = this.getAllColnumsName(rs);
//获取class的所有的方法
Method[] methods = c.getDeclaredMethods();
T t;//实例化对象
String methodName = null;//方法名
String columnName = null;//列名
String typeName = null;//参数类型名
Object val = null;//列对应的值
while(rs.next()){
t = (T)c.newInstance();//实例化一个对象
//获取所有的列
for(int i = 0;i<columnNames.size();i++){
columnName = columnNames.get(i);
val = rs.getObject(columnName);
for(Method m:methods){
methodName = m.getName();
if(("set"+columnName).equalsIgnoreCase(methodName)){
typeName = val.getClass().getName();
if("java.math.BigDecimal".equals(typeName)){
m.invoke(t, rs.getInt(columnName));
}else if("java.lang.String".equals(typeName)){
m.invoke(t, rs.getString(columnName));
}else if("java.lang.Integer".equals(typeName)){
m.invoke(t, rs.getInt(columnName));
}else if("java.sql.Timestamp".equals(typeName)){
m.invoke(t, rs.getTimestamp(columnName));
}
}
}
}
list.add(t);
}
}catch(Exception e){
e.printStackTrace();
}finally {
this.closeAll(rs, pstmt, con);
}
return list;
}
/**
* 获取单行值
* @param <T>
* @param sql
* @param params
* @param c
* @return
*/
public <T> T findOne(String sql,List<Object> params,Class c){
Connection con=null;
PreparedStatement pstmt=null;
ResultSet rs=null;
try{
con = this.getConnection();
pstmt = con.prepareStatement(sql);
//设置参数
this.setParams(pstmt, params);
//执行
rs = pstmt.executeQuery();
//获取所有的列名
List<String> columnNames = this.getAllColnumsName(rs);
//获取class的所有的方法
Method[] methods = c.getDeclaredMethods();
T t;//实例化对象
String methodName = null;//方法名
String columnName = null;//列名
String typeName = null;//参数类型名
Object val = null;//列对应的值
if(rs.next()){
t = (T)c.newInstance();//实例化一个对象
//获取所有的列
for(int i = 0;i<columnNames.size();i++){
columnName = columnNames.get(i);
val = rs.getObject(columnName);
for(Method m:methods){
methodName = m.getName();
if(("set"+columnName).equalsIgnoreCase(methodName)){
typeName = val.getClass().getName();
if("java.math.BigDecimal".equals(typeName)){
m.invoke(t, rs.getInt(columnName));
}else if("java.lang.String".equals(typeName)){
m.invoke(t, rs.getString(columnName));
}else{//其他数据类型
}
}
}
}
return t;
}
}catch(Exception e){
e.printStackTrace();
}finally {
this.closeAll(rs, pstmt, con);
}
return null;
}
/**
* 使用聚合函数
* @param sql
* @param params
* @return
* @throws SQLException
*/
public int selectPloymer(String sql,List<Object> params) throws SQLException{
Connection con=null;
PreparedStatement pstmt=null;
int result=0;
try {
con=this.getConnection(); //获取连接
//创建预编译执行语句
pstmt=con.prepareStatement(sql);
this.setParams(pstmt, params);
//执行预编译语句，获取结果
result=pstmt.executeUpdate();
} catch (SQLException e) {
e.printStackTrace();
}
return result;
}
/**
* 查询单行数据
* @param sql 要执行的查询语句
* @param params 查询语句中占位符?对应值
* @return 返回满足条件的所有数据
*/
public Map<String,Object> find(String sql,Object ... params){
Connection con=null;
PreparedStatement pstmt=null;
ResultSet rs=null;
Map<String,Object> map=null; //每一个map中存放一行数据
try {
con=this.getConnection(); //获取连接
pstmt=con.prepareStatement(sql); //创建预编译执行语句
this.setParams(pstmt, params); //给预编译执行语句中的占位符赋值
rs=pstmt.executeQuery(); //执行预编译语句获取结果集
ResultSetMetaData rsmd=rs.getMetaData(); //获取结果集中列的信息
int colCount=rsmd.getColumnCount(); //获取结果集中列的数量
String[] colNames=new String[colCount];
for(int i=0;i<colCount;i++){ //通过列的索引循环获取每个列的列名
colNames[i]=rsmd.getColumnName(i+1).toLowerCase();
}
//通过列名循环获取每个列的值
Blob blob;
Object obj=null;
String typeName=null;
byte[] bt=null;
InputStream is=null;
if(rs.next()){ //每循环一次就是一行数据
map=new HashMap<String,Object>();
for(String colName:colNames){ //循环着一行中的每个列，通过每个列的列名获取这个列的值
obj=rs.getObject(colName);
if(obj!=null){
typeName=obj.getClass().getSimpleName();
if("BLOB".equals(typeName)){
try {
blob=(Blob)obj;
bt=new byte[ (int) blob.length() ];
is=blob.getBinaryStream();
is.read(bt);
} catch (IOException e) {
e.printStackTrace();
} finally{
if(is!=null){
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
map.put(colName,bt); //以列名为键，以对应列的值为值
}else{
map.put(colName,obj); //以列名为键，以对应列的值为值
}
}else{
map.put(colName,obj); //以列名为键，以对应列的值为值
}
}
}
} catch (SQLException e) {
e.printStackTrace();
} finally{
this.closeAll(rs, pstmt, con);
}
return map;
}
/**
* 针对聚合查询
* @param sql 要执行的查询语句
* @param params 查询语句中占位符?对应值
* @return 返回满足条件的所有数据
*/
public Map<String,String> get(String sql,Object ... params){
Connection con=null;
PreparedStatement pstmt=null;
ResultSet rs=null;
Map<String,String> map=null; //每一个map中存放一行数据
try {
con=this.getConnection(); //获取连接
pstmt=con.prepareStatement(sql); //创建预编译执行语句
this.setParams(pstmt, params); //给预编译执行语句中的占位符赋值
rs=pstmt.executeQuery(); //执行预编译语句获取结果集
ResultSetMetaData rsmd=rs.getMetaData(); //获取结果集中列的信息
int colCount=rsmd.getColumnCount(); //获取结果集中列的数量
String[] colNames=new String[colCount];
for(int i=0;i<colCount;i++){ //通过列的索引循环获取每个列的列名
colNames[i]=rsmd.getColumnName(i+1).toLowerCase();
}
//通过列名循环获取每个列的值
if(rs.next()){ //每循环一次就是一行数据
map=new HashMap<String,String>();
for(String colName:colNames){ //循环着一行中的每个列，通过每个列的列名获取这个列的值
map.put(colName,rs.getString(colName)); //以列名为键，以对应列的值为值
}
}
} catch (SQLException e) {
e.printStackTrace();
} finally{
this.closeAll(rs, pstmt, con);
}
return map;
}
/**
* 针对聚合查询
* @param sql 要执行的查询语句
* @param params 查询语句中占位符?对应值
* @return 返回满足条件的所有数据
*/
public Map<String,String> getx(String sql,String ... params){
Connection con=null;
PreparedStatement pstmt=null;
ResultSet rs=null;
Map<String,String> map=null; //每一个map中存放一行数据
try {
con=this.getConnection(); //获取连接
pstmt=con.prepareStatement(sql); //创建预编译执行语句
this.setParams(pstmt, params); //给预编译执行语句中的占位符赋值
rs=pstmt.executeQuery(); //执行预编译语句获取结果集
ResultSetMetaData rsmd=rs.getMetaData(); //获取结果集中列的信息
int colCount=rsmd.getColumnCount(); //获取结果集中列的数量
String[] colNames=new String[colCount];
for(int i=0;i<colCount;i++){ //通过列的索引循环获取每个列的列名
colNames[i]=rsmd.getColumnName(i+1).toLowerCase();
}
//通过列名循环获取每个列的值
if(rs.next()){ //每循环一次就是一行数据
map=new HashMap<String,String>();
for(String colName:colNames){ //循环着一行中的每个列，通过每个列的列名获取这个列的值
map.put(colName,rs.getString(colName)); //以列名为键，以对应列的值为值
}
}
} catch (SQLException e) {
e.printStackTrace();
} finally{
this.closeAll(rs, pstmt, con);
}
return map;
}
}
MapperInfo.java
package cn.itcast.mybatis;
/**
* 存储XXMapper.xml 文件 信息
* @author wjc
*
*/
public class MapperInfo {
private String sql;
private String resultType;
private String parameterType;
private boolean isUpdate = true;
@Override
public String toString() {
return "MapperInfo [sql=" + sql + ", resultType=" + resultType + ", parameterType=" + parameterType
+ ", isUpdate=" + isUpdate + "]";
}
public String getSql() {
return sql;
}
public void setSql(String sql) {
this.sql = sql;
}
public String getResultType() {
return resultType;
}
public void setResultType(String resultType) {
this.resultType = resultType;
}
public String getParameterType() {
return parameterType;
}
public void setParameterType(String parameterType) {
this.parameterType = parameterType;
}
public boolean isUpdate() {
return isUpdate;
}
public void setUpdate(boolean isUpdate) {
this.isUpdate = isUpdate;
}
}
MybatisConfig.java
package cn.itcast.mybatis;
import java.io.ByteArrayInputStream;
import java.util.ArrayList;
import java.util.List;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.XPath;
import org.dom4j.io.SAXReader;
/**
* 解析mybatis-config.xml
* @author wjc
*
*/
public class MybatisConfig {
private DataSource data;//数据源信息 driver url username password
private List<String> mappers = new ArrayList<String>();//存储映射文件 mappers
//mybatis-config.xml
public MybatisConfig(String config) throws DocumentException{
this.parseXml(config);
}
/**
* 解析mybatis-config.xml文件
* @param config xml文件路径
* @throws DocumentException
*/
private void parseXml(String config) throws DocumentException{
SAXReader saxReader = new SAXReader();//SAXReader()
/**
* void removeHandler(String path)
Removes the ElementHandler from the event based processor, for the specified path.
*/
Document document = saxReader.read(config);//获取mybatis-config.xml文件的路径
/**
* nodeName
* /从根元素结点
* //从匹配当前元素选择文档中的节点,需要考虑位置
* //data/property 获取data下的所有的property元素
*/
/**
* List selectNodes(Object context)
selectNodes performs this XPath expression on the given Nodeor Listof Nodes instances appending all the results together into a single list.
*/
XPath xpath = document.createXPath("//dataSource/property");//定位到mybatis-config.xml下的dataSource标签下的property
List<Element> list = xpath.selectNodes(document);//获取所有的property结点
data = new DataSource();//创建数据源对象
String qname;
for(Element e:list){
qname = e.attributeValue("name");
/**
* 将标签的属性值放入到数据源对象中
*/
if("driver".equals(qname)){
data.setDriverClassName(e.attributeValue("value"));
}else if("url".equals(qname)){
data.setUrl(e.attributeValue("value"));
}else if("username".equals(qname)){
data.setUser(e.attributeValue("value"));
}else if("password".equals(qname)){
data.setPassword(e.attributeValue("value"));
}
}
xpath = document.createXPath("//mappers/mapper");//定位到定位到mybatis-config.xml下的mappers标签下的mapper
List<Element> list2 = xpath.selectNodes(document);//获取所有的mapper结点
String pname;
for(Element mapper:list2){
pname = mapper.attributeValue("resource");//获取mapper标签的resource属性值
mappers.add(pname);//循环所有的mapper映射文件添加到List集合中
}
}
public DataSource getData() {
return data;
}
public List<String> getMappers() {
return mappers;
}
}
SqlSession.java
package cn.itcast.mybatis;
import java.util.List;
/**
* 创建SqlSession
* @author wjc
*
*/
public class SqlSession {
private SqlSessionFactory factory;
private DBHelper db;
public SqlSession(SqlSessionFactory factory){
//得到相应的SqlSessionFactory对象
this.factory = factory;
//获取相应连接
this.db = new DBHelper(factory.getConfig().getData());
}
public <T> List<T> selectList(String sqlId,List<Object> params){
//根据输入的sqlId 获取相应的sql语句配置信息
MapperInfo mapperinfo = factory.getMapperInfos().get(sqlId);
//非空
if(null != mapperinfo){
try{
//获取sql语句
String sql = mapperinfo.getSql();
//若是跟新操作返回null
if(mapperinfo.isUpdate()){
return null;
}
//获取返回值
String className = mapperinfo.getResultType();
//得到返回值对象的类 比如 String --> java.lang.String
Class<?> c = Class.forName(className);
//获取结果
return db.findAll(sql, params, c);
}catch(Exception e){
e.printStackTrace();
}
}
return null;
}
}
SqlSessionFactory.java
package cn.itcast.mybatis;
import java.io.File;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.XPath;
import org.dom4j.io.SAXReader;
/**
* 创建SqlSessionFactory
* @author wjc
* 解析Deptment.xml
*/
public class SqlSessionFactory {
private MybatisConfig config;
private Map<String,MapperInfo> mapperInfos = new HashMap<String,MapperInfo>();
public SqlSessionFactory(MybatisConfig config) throws DocumentException{
this.config = config;
this.parseXml();
}
private void parseXml() throws DocumentException{
List<String> mappers = config.getMappers();//获取mybatis-config.xml下所有的mapper标签
if(mappers != null && mappers.size()>0){//若mapers非空
SAXReader saxReader = new SAXReader();
for(String mapper:mappers){
//开始解析Deptment.xml
File file = new File("src/main/resources/"+mapper);
Document document = saxReader.read(file);
//获取Deptment.xml下的mapper的所有标签
XPath xpath = document.createXPath("//mapper/*");
List<Element> list = xpath.selectNodes(document);
MapperInfo info = null;
String qname = null;
for(Element e :list){
info = new MapperInfo();//创建MapperInfo对象
qname = e.getName();
if("select".equals(qname)){
info.setUpdate(false);
}
info.setParameterType(e.attributeValue("parameterType"));
info.setResultType(e.attributeValue("resultType"));
info.setSql(e.getTextTrim());
mapperInfos.put(e.attributeValue("id"), info);//将id与sql语句的相关配置向关联
}
}
}
}
public MybatisConfig getConfig() {
return config;
}
public Map<String, MapperInfo> getMapperInfos() {
return mapperInfos;
}
}
MyTest.java
package hello4;
import java.util.List;
import org.dom4j.DocumentException;
import org.junit.Test;
import cn.itcast.bean.DeptmentBean;
import cn.itcast.mybatis.MybatisConfig;
import cn.itcast.mybatis.SqlSession;
import cn.itcast.mybatis.SqlSessionFactory;
public class MyTest {
@Test
public void show() throws DocumentException{
String name = "src/main/resources/mybatis-config.xml";
SqlSessionFactory fact =new SqlSessionFactory(new MybatisConfig(name));
SqlSession session = new SqlSession(fact);
List<DeptmentBean> list = session.selectList("get", null);
System.out.println(list);
}
}
运行结果
DeptmentBean [deptId=1, deptName=技术部, discrbe=湖南]
DeptmentBean [deptId=3, deptName=行政部, discrbe=湖南衡阳]
DeptmentBean [deptId=4, deptName=市场部, discrbe=湖南]
DeptmentBean [deptId=5, deptName=xx, discrbe=sss]
DeptmentBean [deptId=6, deptName=xx, discrbe=sss]
DeptmentBean [deptId=7, deptName=xx, discrbe=sss]
DeptmentBean [deptId=8, deptName=xx, discrbe=sss]