gson使用在android使用例子

Java代码  

虽然android自带了json处理，但是没有封装，总觉得不方便，网上找了gson的处理，觉得还行。  

Java代码   
//转换器   
        GsonBuilder builder = new GsonBuilder();    
        // 不转换没有 @Expose 注解的字段    
        builder.excludeFieldsWithoutExposeAnnotation();   
        Gson gson = builder.create();    
           
        //1、对象转string   
        Student stu = new Student();   
        stu.setStudentId(333);   
        stu.setStudentName("qqq");   
        String stuStr = gson.toJson(stu);   
        System.out.println(stuStr); //{"studentName":"qqq","studentId":333}   
           
           
        //2、string转对象   
        Student user2 = gson.fromJson(stuStr, Student.class);    
        System.out.println(user2);    
        String stuTemp = "{"studentName":"qqq2","studentId":3335}";   
        Student user4 = gson.fromJson(stuTemp, Student.class);    
        System.out.println(user4);    
  
        //3、对象List转string   
        List testBeanList = new ArrayList();    
        Student testBean = new Student();    
        testBean.setStudentId(555);   
        testBean.setStudentName("552");   
        testBeanList.add(testBean);    
           
        //Gson gsonList = new Gson();    
        Type type = new TypeToken>(){}.getType();  //指定集合对象属性   
        String beanListToJson = gson.toJson(testBeanList, type);    
        System.out.println(beanListToJson); //[{"studentName":"552","studentId":555}]    
  
        //集合string转对象list   
        List testBeanListFromJson = gson.fromJson(beanListToJson, type);    
        System.out.println(testBeanListFromJson); //[555:552]   
  
        //4、集合如果不指定类型 默认为String   
        List testList = new ArrayList();    
        testList.add("first");    
        testList.add("second");    
        String listToJson = gson.toJson(testList);    
        System.out.println(listToJson); //["first","second"]    
           
        //5、集合字符串转回来需要指定类型   
        List testList2 = (List) gson.fromJson(listToJson,    
          new TypeToken>() {    
          }.getType());    
        System.out.println(testList2);    
  
        //6、 将HashMap字符串转换为 JSON    
        Map testMap = new HashMap();    
        testMap.put("id", "id.first");    
        testMap.put("name", "name.second");    
        String mapToJson = gson.toJson(testMap);    
        System.out.println(mapToJson); //{"id":"id.first","name":"name.second"}   
        //7、stringMap转对象   
        Map userMap2 = (Map) gson.fromJson(mapToJson,    
                new TypeToken>() {    
            }.getType());    
        System.out.println(userMap2); //{id=id.first, name=name.second}    
  
        //8、对象含有普通对象、集合、map情况   
        Student user1 = new Student();    
        user1.setStudentId(1001);    
        user1.setStudentName("张三");    
           
        Student user3 = new Student();    
        user3.setStudentId(1002);    
        user3.setStudentName("李四");    
           
        Map userMap = new HashMap();    
        userMap.put("user1", user1);    
        userMap.put("user3", user3);    
           
        List userList = new ArrayList();    
        userList.add(user1);    
        userList.add(user3);    
           
        Teacher groupBean = new Teacher();    
        groupBean.setStudent(user1);   
        groupBean.setStus(userList);   
        groupBean.setMap((HashMap)userMap);   
        //groupBean.setUserList(userList);    
        Gson gsonGroup = new Gson();    
  
        String sGroupBean = gsonGroup.toJson(groupBean, new TypeToken() {    
            }.getType());    
        System.out.println(sGroupBean);

         

Java代码  

//9、复杂对象string转对象   
Teacher groupBean2 = (Teacher) gson.fromJson(sGroupBean,    
   new TypeToken() {    
   }.getType());    
System.out.println(groupBean2);   
 

Java代码   
package com.andtools;   
  
import com.google.gson.annotations.Expose;   
  
public class Student {   
    @Expose  
    private String studentName;   
    @Expose  
    private int studentId;   
    public Student(){}   
    public Student(int studentId,String studentName){   
        this.setStudentId(studentId);   
        this.setStudentName(studentName);   
    }   
    public String toString(){   
        return this.getStudentId() + ":" + this.getStudentName();   
    }   
    public String getStudentName() {   
        return studentName;   
    }   
    public void setStudentName(String studentName) {   
        this.studentName = studentName;   
    }   
    public int getStudentId() {   
        return studentId;   
    }   
    public void setStudentId(int studentId) {   
        this.studentId = studentId;   
    }   
       
}

Java代码  

package com.andtools;   
  
import java.util.HashMap;   
import java.util.List;   
import java.util.Map;   
  
import com.google.gson.annotations.Expose;   
  
public class Teacher {   
    @Expose  
    private int id;   
    @Expose  
    private String name;   
    @Expose  
    private int age;   
    @Expose  
    private Student student;   
    @Expose  
    private List stus;   
    @Expose  
    private HashMap map;   
    public String toString(){   
        return this.getId()+":"+this.getName()+":"+this.getAge() +":"+ this.getStudent().toString() + ":" + this.getStus() + ":" + this.getMap();   
    }   
    public int getId() {   
        return id;   
    }   
    public void setId(int id) {   
        this.id = id;   
    }   
    public String getName() {   
        return name;   
    }   
    public void setName(String name) {   
        this.name = name;   
    }   
    public int getAge() {   
        return age;   
    }   
    public void setAge(int age) {   
        this.age = age;   
    }   
    public Student getStudent() {   
        return student;   
    }   
    public void setStudent(Student student) {   
        this.student = student;   
    }   
    public List getStus() {   
        return stus;   
    }   
    public void setStus(List stus) {   
        this.stus = stus;   
    }   
    public HashMap getMap() {   
        return map;   
    }   
    public void setMap(HashMap map) {   
        this.map = map;   
    }   
       
}