Spring Data Jpa自定义关联查询

Spring Data Jpa自定义关联查询，可以使用原生SQL，也可以使用JPQL语法。
原生SQL返回数组对象List<Object[]>；JPQL返回自定义对象List<ViewUserInfo>
ViewUserInfo.java

/**
 * 自定义实体
 */
public class ViewUserInfo {
	//table: user info
	private Integer id;
    private String name;
    private String username;
    //table: role
    private long roleId;
    //table: permission
    private String url;
    private String permission; 
    
    public ViewUserInfo(){
    }
    //构造函数，JPQL自定义查询将引用
    public ViewUserInfo(int userId,String username,String name,
    				long roleid,String url,String permission){
    	this.id=userId;
    	this.username=username;
    	this.name=name;
    	this.roleId= roleid;
    	this.url=url;
    	this.permission=permission;
    }    
	
	set,get...

}

JpaUserRepository.java

//查询方法定义 SQL
@Query(value = "select "
+" a.id as userId,a.username,a.name,b.role_id as roleId,d.url,d.permission "
+" from user_info a, sys_user_role b, sys_role_permission c,sys_permission d "
+" where a.id=b.u_id and b.role_id=c.role_id and c.permission_id=d.id",
	nativeQuery = true)//原生SQL
public List<Object[]> findByNameSQL(String name);
//查询方法定义 JPQL
@Query(value = "select new com.test.demo.model.ViewUserInfo("
+" a.id,a.username,a.name,b.roleid,c.url,c.permission ) "
+" from JpaUser a, SysUserRole b, SysPermission c "
+" where a.id=b.uid and b.roleid=c.id")
public List<ViewUserInfo> findByName(String name);

JpaController.java

//原生SQL
@RequestMapping("/jpa/getSql")
public String getNameSql(Model model, @RequestParam String name) {
	List<Object[]> users = userRepository.findByNameSQL(name);
	for(Object[] objs : users){
		System.out.println("----");
		for(int i = 0,j=objs.length; i < j; i++){
			System.out.println("--"+objs[i]);
		}
	}
	model.addAttribute("users", users);
	return "/jpa/listSql";
}
//JPQL
@RequestMapping("/jpa/getJpql")
public String getName(Model model, @RequestParam String name) {
	List<ViewUserInfo> users = userRepository.findByName(name);
	for(ViewUserInfo user : users){
		System.out.println("----");
		System.out.println("----"+user.getName());
		System.out.println("----"+user.getUrl());
	}
	model.addAttribute("users", users);
	return "/jpa/listJpql";
}

JPQL自定义语法中的对象是对应每个表的JOPO，不再逐一罗列
SysUserRole.java

@Entity
@Table(name = "sys_user_role")
public class SysUserRole {
	@Id
	private Integer id;
	@Column(name="role_id")
	private Long roleid;
	@Column(name="u_id")
	private Long uid;
	
	get,set...
}

jopo
listSql.html文件路径为main\resources\templates\jpa，注意css的引入路径
同时thymeleaf遍历数组 List<Object[]的写法

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8"/>
    <title>用户角色列表-userRoleList</title>
    <link rel="stylesheet" th:href="@{../css/bootstrap.css}" />
</head>
<body class="container">
<br/>
<h1>用户角色列表</h1>
<br/><br/>
<div class="with:80%">
    <table class="table table-hover">
        <thead>
        <tr>
            <th>#</th>
            <th>账号</th>
            <th>昵称</th>
            <th>角色ID</th>
            <th>url</th>
            <th>permission</th>
        </tr>
        </thead>
        <tbody>
		<!--遍历数组 List<Object[]> -->
		<!--与ViewUserInfo构造方法中的参数顺序保持一致-->
		<!--userId, username, name, roleid, url, permission-->
        <tr th:each="user,itemStat:${users}">
            <th scope="row" th:text="${itemStat.count}">1</th>
            <td th:text="${user[1]}">.</td>
            <td th:text="${user[2]}">.</td>
            <td th:text="${user[3]}">.</td>
            <td th:text="${user[4]}">.</td>
            <td th:text="${user[5]}">.</td>
        </tr>
        </tbody>
    </table> 
</div>
</body>
</html>

测试
调用controler中的方法http://cos6743:8081/jpa/getJpql?name=test11
eclipse控制台
jpql
网页
jpql
调用controler中的方法http://cos6743:8081/jpa/getSql?name=test11
sql

Spring Data Jpa自定义关联查询

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