安卓第8次课：jackson和httpcliet

一，jackson
Java->Json
1 ObjectMap
2 JsonGenerator
3 @JsonIgnore
hibernate中一对多、多对多双向关联会出现这种死循环

二，HttpClient
1、简介：
HttpClient是Apache Jakarta Common下的子项目，用来提供高效的、最新的、
功能丰富的支持HTTP协议的客户端编程工具包，并且它支持HTTP协议最新的版本和协议
2、Android已成功集成了HttpClient，这意味这开发人员可以直接在Android应用中使用
HtppClient来提交请求、接收响应

  注：在API 23中，Google已经移除了移除了Apache HttpClient相关的类 ，
  在build.gradle中的android {}中加上useLibrary 'org.apache.http.legacy'，
  详情见资料“”

============================================================================================
案例一：HttpClient的使用步骤
1 创建HttpClient对象
HttpClient httpClient = new DefaultHttpClient();

2 创建HttpGet(或HttpPost)对象
  HttpGet HttpGet = new HttpGet("http://www.baidu.com");
  HttpPost httpPost = new HttpPost("http://www.baidu.com");

3 添加参数(可选)
setParams(HttpParams params)//HttpGet和HttpPost共有
setEntity(HttpEntity entity)//HttpPost独有

    List<NameValuePair> params = new ArrayList<NameValuePair>();
    params.add(new BasicNameValuePair("age", "20"));
    params.add(new BasicNameValuePair("like", "aa"));
    params.add(new BasicNameValuePair("like", "bb"));
    params.add(new BasicNameValuePair("like", "cc"));
    params.add(new BasicNameValuePair("newsCategoryId", "1"));
    HttpEntity paramEntity = new UrlEncodedFormEntity(params,"UTF-8");
    httpPost.setEntity(paramEntity);

4 发送GET(或POST)请求，并获得响应
HttpResponse httpResponse = httpClient.execute(HttpUriRequest request);

  注1：HttpUriRequest为HttpGet和HttpPost的父类
  注2：需要添加允许网络访问权限，不然会报错“java.lang.SecurityException: Permission denied (missing INTERNET permission?)”
       <uses-permission android:name="android.permission.INTERNET" />

  注3：如果地址错误，或服务器未开户，HttpClient这SB会等待N久(>24小时)。
       所以请记得设置超时时间，所以请记得设置超时时间，所以请记得设置超时时间
       所以请记得设置超时时间，所以请记得设置超时时间，所以请记得设置超时时间
       所以请记得设置超时时间，所以请记得设置超时时间，所以请记得设置超时时间

       另外HttpClient版本不一样，代码也不一样。下面的4.0版本的写法
       httpClient.getParams().setParameter(CoreConnectionPNames.CONNECTION_TIMEOUT, 2000);// 连接时间
       httpClient.getParams().setParameter(CoreConnectionPNames.SO_TIMEOUT, 2000);// 数据传输时间

5 处理响应
（1）响应状态码(200)
httpResponse.getStatusLine().getStatusCode()

（2）响应头
getAllHeaders()/getHeaders(String name)

（3） 响应内容
      HttpEntity httpEntity = httpResponse.getEntity();//此对象包含服务器的响应内容
      String result = EntityUtils.toString(httpEntity);

案例二：使用HttpClientUtils与服务器通信

Android客户端与服务器通信

1 JSON数据交换
android系统内置了对象json的支持，另外json其实就以下几个对象的使用：
JSONObject、JSONArray、JSONStringer、JSONException
2 web service，底层使用xml交换数据

补充：
1、关于org.apache.http.conn.HttpHostConnectException: Connection to refused错误的解决办法
2、增加网络访问权限：
找到 AndroidManifest.xml 文件。在application标签后面加上
3、检查ip地址：
启动的android模拟器吧自己也当成127.0.0.1和localhost，如果使用了localhost或者127.0.0.1则会被拒绝访问，
把ip地址改成实际地址，如：192.168.1.5

============================================================================================

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实例：
增删查改：
xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/bt_main_add"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="新增" />

    <Button
        android:id="@+id/bt_main_edit"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="修改" />

    <Button
        android:id="@+id/bt_main_del"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="删除" />

    <Button
        android:id="@+id/bt_main_load"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="查单个" />

    <Button
        android:id="@+id/bt_main_list"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="查全部" />


</LinearLayout>

MainActivity.java

package com.example.t212_a08;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;

import com.fasterxml.jackson.databind.ObjectMapper;

import java.io.IOException;
import java.util.Map;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private Button bt_main_add;
    private Button bt_main_edit;
    private Button bt_main_del;
    private Button bt_main_load;
    private Button bt_main_list;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //查找控件
        findViews();

        //绑定监听器
        bt_main_add.setOnClickListener(this);
        bt_main_edit.setOnClickListener(this);
        bt_main_del.setOnClickListener(this);
        bt_main_load.setOnClickListener(this);
        bt_main_list.setOnClickListener(this);

    }

    private void findViews() {
        bt_main_add = (Button) findViewById(R.id.bt_main_add);
        bt_main_edit = (Button) findViewById(R.id.bt_main_edit);
        bt_main_del = (Button) findViewById(R.id.bt_main_del);
        bt_main_load = (Button) findViewById(R.id.bt_main_load);
        bt_main_list = (Button) findViewById(R.id.bt_main_list);
    }


    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.bt_main_add:
                add();
                break;
            case R.id.bt_main_edit:
                edit();
                break;
            case R.id.bt_main_del:
                del();
                break;
            case R.id.bt_main_load:
                load();
                break;
            case R.id.bt_main_list:
                list();
                break;
        }
    }

    private void add() {
        Log.i("test", "add...");
        //定义查询的方法
        HttpClientPost post = new HttpClientPost("/jsp/userAction.action");
        //定义要查询的条件
        post.addParam("methodName","userAdd");
        post.addParam("uid","007");
        post.addParam("uname","lixiao");
        post.addParam("roleid","001");
        post.addParam("upwd","123456");
        //点击回车键查询
        post.submit(new HttpClientPost.Callback() {
            @Override
            public void execute(String json) {
                Log.i("server22:" ,json);
            }
        });
    }
    //修改
    private void edit() {
        Log.i("test", "edit...");
        //定义查询的方法
        HttpClientPost post = new HttpClientPost("/jsp/userAction.action");
        //定义要查询的条件
        post.addParam("methodName","userUpdate");
        post.addParam("SerialNo","1");
        post.addParam("uid","001");
        post.addParam("uname","张三3333");
        post.addParam("roleid","001");
        post.addParam("upwd","123456");
        //点击回车键查询
        post.submit(new HttpClientPost.Callback() {
            @Override
            public void execute(String json) {
                Log.i("server22:" ,json);
            }
        });
    }
    //删除
    private void del() {
        Log.i("test", "del...");
        //定义查询的方法
        HttpClientPost post = new HttpClientPost("/jsp/userAction.action");
        //定义要查询的条件
        post.addParam("methodName","userDelete");
        post.addParam("SerialNo","1");
        //点击回车键查询
        post.submit(new HttpClientPost.Callback() {
            @Override
            public void execute(String json) {
                Log.i("server3:" ,json);
            }
        });

    }

    //查询单个
    private void load() {
        Log.i("test", "load...");
        //定义查询的方法
        HttpClientPost post = new HttpClientPost("/jsp/userAction.action");
        //定义要查询的条件
        post.addParam("methodName","userList");
        post.addParam("uname","123123");

        //点击回车键查询
        post.submit(new HttpClientPost.Callback() {
            @Override
            public void execute(String json) {
                ObjectMapper om = new ObjectMapper();
                try {
                    Map map = om.readValue(json, Map.class);
                    Log.i("server:" ,map.get("total").toString());
                    //获取要查询的类型
                    Log.i("server:" ,map.get("rows").getClass().getName());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });
    }

    //查询所有
    private void list() {
        Log.i("test", "list...");
        //定义查询的方法
        HttpClientPost post = new HttpClientPost("/jsp/userAction.action");
        //定义要查询的条件
        post.addParam("methodName","userList");

        //点击回车键查询
        post.submit(new HttpClientPost.Callback() {
            @Override
            public void execute(String json) {
                Log.i("server11:" ,json);
            }
        });
    }
}

HttpClientPost.java

package com.example.t212_a08;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.params.CoreConnectionPNames;
import org.apache.http.util.EntityUtils;

import android.os.AsyncTask;

/**
 * 封装 HttpClient对象POST请求
 *
 */
public class HttpClientPost implements Serializable {

    private static final long serialVersionUID = 1777547416049652217L;

    private static HttpClient httpClient = new DefaultHttpClient();

    static {
        httpClient.getParams().setParameter(
                CoreConnectionPNames.CONNECTION_TIMEOUT, 2000);// 连接时间
        httpClient.getParams().setParameter(CoreConnectionPNames.SO_TIMEOUT,
                3000);// 数据传输时间
    }

    // 字符集
    private static String encoding = "UTF-8";

    // 服务器地址+端口号+项目名
    private static String basePath = "http://192.168.43.158:8080/T212_easyui";

    // 子控制器的路径
    private String path;

    // 保存请求中的参数
    private List<NameValuePair> params = new ArrayList<NameValuePair>();;

    public HttpClientPost(String path) {
        super();
        this.path = path;
    }

    /**
     * 向POST请求中添加参数
     *
     * @param name
     * @param value
     */
    public void addParam(String name, String value) {
        if (value == null) {
            params.add(new BasicNameValuePair(name, ""));
        } else {
            params.add(new BasicNameValuePair(name, value));
        }
    }

    /**
     * 提交POST请求
     */
    @SuppressWarnings("unchecked")
    public void submit(final HttpClientPost.Callback callback) {
        new AsyncTask() {
            private String json;

            @Override
            protected Object doInBackground(Object... args) {
                try {
                    // 1. 创建HttpClient对象

                    // 2. 创建HttpGet(或HttpPost)对象
                    HttpPost httpPost = new HttpPost(basePath + path);

                    // 3. 向POST请求中添加参数(可选)
                    if (0 != params.size()) {
                        HttpEntity paramEntity = new UrlEncodedFormEntity(
                                params, encoding);
                        httpPost.setEntity(paramEntity);
                    }

                    // 4. 发送POST请求，并获得响应
                    HttpResponse httpResponse = httpClient.execute(httpPost);

                    // 5. 处理响应
                    if (200 == httpResponse.getStatusLine().getStatusCode()) {
                        HttpEntity responseEntity = httpResponse.getEntity();// 此对象包含服务器的响应内容
                        this.json = EntityUtils.toString(responseEntity);
                    }
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
                return null;
            }

            protected void onPostExecute(Object result) {
                callback.execute(this.json);
            }


        }.execute();
    }

    public static interface Callback {
        void execute(String json);
    }
}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.t212_a08">


    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

安卓第8次课：jackson和httpcliet

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