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表结构

SQL结构和数据

DROP TABLE IF EXISTS `demo`;CREATE TABLE `demo` (  `id` int(11) NOT NULL AUTO_INCREMENT,  `pid` int(11) NOT NULL,  `name` varchar(255) COLLATE utf8_unicode_ci NOT NULL,  PRIMARY KEY (`id`)) ENGINE=InnoDB AUTO_INCREMENT=8 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;INSERT INTO `demo` VALUES ('1', '0', 'A');INSERT INTO `demo` VALUES ('2', '1', 'B');INSERT INTO `demo` VALUES ('3', '1', 'C');INSERT INTO `demo` VALUES ('4', '2', 'D');INSERT INTO `demo` VALUES ('5', '2', 'E');INSERT INTO `demo` VALUES ('6', '3', 'F');INSERT INTO `demo` VALUES ('7', '3', 'G');

Pom文件

   
                
    
     org.springframework.boot
                
    
     spring-boot-starter-web
            
            
   
                
    
     com.alibaba
                
    
     druid
                
    
     1.1.1
            
           
   
                
    
     mysql
                
    
     mysql-connector-java
                
    
     5.1.39
            
            
   
                
    
     org.mybatis.spring.boot
                
    
     mybatis-spring-boot-starter
                
    
     1.2.0
            
   

application.properties文件

spring.datasource.url=jdbc:mysql://127.0.0.1:3306/treespring.datasource.username=rootspring.datasource.password=1234spring.datasource.driver-class-name=com.mysql.jdbc.Driver

TreeMapper

@Mapperpublic interface TreeMapper {     @Select("select * from demo")    List
   
     getAll(); }
   

对应数据库的Tree实体类

public class Tree {        private Integer id;    private Integer pid;    private String name;    public Integer getId() {        return id;    }    public void setId(Integer id) {        this.id = id;    }    public Integer getPid() {        return pid;    }    public void setPid(Integer pid) {        this.pid = pid;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    @Override    public String toString() {        return "Tree{" +                "id=" + id +                ", pid=" + pid +                ", name='" + name + '\'' +                '}';    }}

NewTree，定义返回给前段的树类型，根据业务不同自行修改（这里为了简单起见，只修改了id和pid的类型）

public class NewTree {    private String id;    private String pid;    private String name;    public String getId() {        return id;    }    public void setId(String id) {        this.id = id;    }    public String getPid() {        return pid;    }    public void setPid(String pid) {        this.pid = pid;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    @Override    public String toString() {        return "Tree{" +                "id=" + id +                ", pid=" + pid +                ", name='" + name + '\'' +                '}';    }}

MenuTreeUtil，递归构造树形结构

@Componentpublic class MenuTreeUtil {        //已经被buildTree的list集合    private List
   
     menuCommon;    //返回给前端的NewTree List集合    private List
    
   

TreeController

@Controllerpublic class TreeController {    @Resource    TreeMapper treeMapper;    @Resource    MenuTreeUtil menuTreeUtil;        @RequestMapping(value = "/menuList",method = {RequestMethod.GET})    @ResponseBody    public String getTree() throws Exception {            List
   
     list = buildTree(treeMapper.getAll());        List
    
   

启动项目，并在地址栏输入如下地址即可

结果展示（JSON在线解析）

[{	id = 1,	name = A,	pid = 0,	childList = [{		id = 2,		name = B,		pid = 1,		childList = [{			id = 4,			name = D,			pid = 2,			childList = []		}, {			id = 5,			name = E,			pid = 2,			childList = []		}]	}, {		id = 3,		name = C,		pid = 1,		childList = [{			id = 6,			name = F,			pid = 3,			childList = []		}, {			id = 7,			name = G,			pid = 3,			childList = []		}]	}]}]

参考 

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