安卓开发 gson使用在android使用例子

作者:Young.Liu 分类: 技术 发布于:2013-9-11 14:41 ė1932次浏览 60条评论
  1. 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。  


//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<Student> testBeanList = new ArrayList<Student>(); 
        Student testBean = new Student(); 
        testBean.setStudentId(555);
        testBean.setStudentName("552");
        testBeanList.add(testBean); 
        
        //Gson gsonList = new Gson(); 
        Type type = new TypeToken<List<Student>>(){}.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<Student> 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<String> testList = new ArrayList<String>(); 
        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<String> testList2 = (List<String>) gson.fromJson(listToJson, 
          new TypeToken<List<String>>() { 
          }.getType()); 
        System.out.println(testList2); 

        //6、 将HashMap字符串转换为 JSON 
        Map<String, String> testMap = new HashMap<String, String>(); 
        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<String, String> userMap2 = (Map<String, String>) gson.fromJson(mapToJson, 
        		new TypeToken<Map<String, String>>() { 
	    	}.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<String, Student> userMap = new HashMap<String, Student>(); 
        userMap.put("user1", user1); 
        userMap.put("user3", user3); 
        
        List<Student> userList = new ArrayList<Student>(); 
        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<Teacher>() { 
        	}.getType()); 
        System.out.println(sGroupBean); 
        /*{"stus":[{"studentName":"张三","studentId":1001},{"studentName":"李四","studentId":1002}],"student":{"studentName":"张三","studentId":1001},"map":{"user3":{"studentName":"李四","studentId":1002},"user1":{"studentName":"张三","studentId":1001}},"id":0,"age":0}*/



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



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;
	}
	
}


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;
	}
	
}


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