java--gson：很方便的json拼接和解析的工具类

超、凢脫俗 2023-11-02 06:23 74阅读 0赞

#### 需要导入gson包：gson-2.3.1.jar ，gson-2.3.1-sources.jar ####

#### 测试实体类： ####

public class model {
    
    	private String Name1;
    	private String Name2;
    	private String Name3;
    	
    	public model() {
    		super();
    	}
    	public model(String name1, String name2, String name3) {
    		super();
    		Name1 = name1;
    		Name2 = name2;
    		Name3 = name3;
    	}
    
    	@Override
    	public String toString() {
    		return "model [Name1=" + Name1 + ", Name2=" + Name2 + ", Name3="
    				+ Name3 + "]";
    	}
    	public String getName1() {
    		return Name1;
    	}
    	public void setName1(String name1) {
    		Name1 = name1;
    	}
    	public String getName2() {
    		return Name2;
    	}
    	public void setName2(String name2) {
    		Name2 = name2;
    	}
    	public String getName3() {
    		return Name3;
    	}
    	public void setName3(String name3) {
    		Name3 = name3;
    	}
    	
    }

### 1：实体类和json数据的相互转化： ###

public static void main(String[] args) {
    		
    		Gson gson = new Gson();
    		model model1 = new model("value1","value2","value3");
    		String JsonMsg1 = gson.toJson(model1);
    		System.out.println("实体类——转——json: " + JsonMsg1);
    		
    		model model2 = gson.fromJson("{\"Name1\":\"value1\",\"Name2\":\"value2\",\"Name3\":\"value3\"}", model.class);
    		//也可以直接用上面生成的json字符串JsonMsg1
    		//model model2 = gson.fromJson(JsonMsg1, model.class);
    		System.out.println("json——转——实体类" + model2.toString());
    		
        }

#### 结果： ####

实体类——转——json: {"Name1":"value1","Name2":"value2","Name3":"value3"}
    json——转——实体类model [Name1=value1, Name2=value2, Name3=value3]

### 2：map和json数据的相互转化： ###

public static void main(String[] args) { 
            Gson gson = new Gson();
    		Map<String,String> map1 = new HashMap<String, String>();
    		map1.put("Name1", "value1");
    		map1.put("Name2", "value2");
    		map1.put("Name3", "value3");
    		String JsonMsg2 = gson.toJson(map1);
    		System.out.println("map——转——json: " + JsonMsg2);
    		
    		Map<String,String> map2 = gson.fromJson("{\"Name1\":\"value1\",\"Name2\":\"value2\",\"Name3\":\"value3\"}", Map.class);
    		System.out.println("json——转——map: " + map2);
        }

#### 结果： ####

map——转——json: {"Name3":"value3","Name2":"value2","Name1":"value1"}
    json——转——map: {Name1=value1, Name2=value2, Name3=value3}

### 3：实体类list和json数据的相互转化： ###

public static void main(String[] args) {
            Gson gson = new Gson();
    		ArrayList<model> list1 = new ArrayList<model>();
    		model model1 = new model("value11","value12","value13");
    		model model2 = new model("value21","value22","value23");
    		model model3 = new model("value31","value32","value33");
    		list1.add(model1);
    		list1.add(model2);
    		list1.add(model3);
    		String JsonMsg3 = gson.toJson(list1);
    		System.out.println("list——转——json: " + JsonMsg3);		
    		
    		ArrayList<model> list2 = (ArrayList<model>) gson.fromJson("[{\"Name1\":\"value1\",\"Name2\":\"value2\",\"Name3\":\"value3\"},{\"Name1\":\"value1\",\"Name2\":\"value2\",\"Name3\":\"value3\"},{\"Name1\":\"value31\",\"Name2\":\"value32\",\"Name3\":\"value33\"}]", List.class);
    		System.out.println("json——转——List: ");
    		for (Object temp : list2) {
    			System.out.print(gson.fromJson((temp).toString(), model.class) + "-");
    		}
        }

#### 结果： ####

list——转——json: [{"Name1":"value11","Name2":"value12","Name3":"value13"},{"Name1":"value21","Name2":"value22","Name3":"value23"},{"Name1":"value31","Name2":"value32","Name3":"value33"}]
    json——转——List: 
    model [Name1=value1, Name2=value2, Name3=value3]-model [Name1=value1, Name2=value2, Name3=value3]-model [Name1=value31, Name2=value32, Name3=value33]-

## 创建修改实体类，创建另一个实体类： ##

model.java

public class model {
    
    	private String Name1;
    	private String Name2;
    	private String Name3;
    	private model2 model2 ;
    	
    	public model() {
    		super();
    	}
    	public model(String name1, String name2, String name3,
    			com.json.test.model2 model2) {
    		super();
    		Name1 = name1;
    		Name2 = name2;
    		Name3 = name3;
    		this.model2 = model2;
    	}
    	
    	@Override
    	public String toString() {
    		return "model [Name1=" + Name1 + ", Name2=" + Name2 + ", Name3="
    				+ Name3 + ", model2=" + model2 + "]";
    	}
    	public model2 getModel2() {
    		return model2;
    	}
    	public void setModel2(model2 model2) {
    		this.model2 = model2;
    	}
    	public String getName1() {
    		return Name1;
    	}
    	public void setName1(String name1) {
    		Name1 = name1;
    	}
    	public String getName2() {
    		return Name2;
    	}
    	public void setName2(String name2) {
    		Name2 = name2;
    	}
    	public String getName3() {
    		return Name3;
    	}
    	public void setName3(String name3) {
    		Name3 = name3;
    	}
    	
    }

model2.java

public class model2 {
    
    	private String Name4;
    	private String Name5;
    	
    	public model2() {
    		super();
    	}
    
    	public model2(String name4, String name5) {
    		super();
    		Name4 = name4;
    		Name5 = name5;
    	}
    
    	
    	@Override
    	public String toString() {
    		return "model2 [Name4=" + Name4 + ", Name5=" + Name5 + "]";
    	}
    
    	public String getName4() {
    		return Name4;
    	}
    
    	public void setName4(String name4) {
    		Name4 = name4;
    	}
    
    	public String getName5() {
    		return Name5;
    	}
    
    	public void setName5(String name5) {
    		Name5 = name5;
    	}
    	
    	
    }

### 4：实体类嵌套另一个实体类 和 json 数据的相互转换： ###

public static void main(String[] args) {
    		Gson gson = new Gson();
    		model2 model4 = new model2("value4" , "value5");
    		model model1 = new model("value1","value2","value3",model4);
    		model1.setModel2(model4);
    		String JsonMsg4 = gson.toJson(model1);
    		System.out.println("实体类嵌套另一个实体类——转——json: " + JsonMsg4);
    		
    		model model5 = gson.fromJson(JsonMsg4, model.class);
    		System.out.println("json——转——实体类嵌套另一个实体类" + model5.toString());
        }

#### 结果： ####

实体类嵌套另一个实体类——转——json: {"Name1":"value1","Name2":"value2","Name3":"value3","model2":{"Name4":"value4","Name5":"value5"}}
    json——转——实体类嵌套另一个实体类model [Name1=value1, Name2=value2, Name3=value3, model2=model2 [Name4=value4, Name5=value5]]

## 再次修改实体类model.java ##

import java.util.ArrayList;
    
    public class model {
    
    	private String Name1;
    	private String Name2;
    	private String Name3;
    	private ArrayList<model2> modelList ;
    	
    	public model() {
    		super();
    	}
    
    	public model(String name1, String name2, String name3,
    			ArrayList<model2> modelList) {
    		super();
    		Name1 = name1;
    		Name2 = name2;
    		Name3 = name3;
    		this.modelList = modelList;
    	}
    	@Override
    	public String toString() {
    		return "model [Name1=" + Name1 + ", Name2=" + Name2 + ", Name3="
    				+ Name3 + ", modelList=" + modelList + "]";
    	}
    	public ArrayList<model2> getModelList() {
    		return modelList;
    	}
    	public void setModelList(ArrayList<model2> modelList) {
    		this.modelList = modelList;
    	}
    	public String getName1() {
    		return Name1;
    	}
    	public void setName1(String name1) {
    		Name1 = name1;
    	}
    	public String getName2() {
    		return Name2;
    	}
    	public void setName2(String name2) {
    		Name2 = name2;
    	}
    	public String getName3() {
    		return Name3;
    	}
    	public void setName3(String name3) {
    		Name3 = name3;
    	}
    	
    }

### 5:实体类嵌套另一个实体类list 和 json 数据的相互转换： ###

public static void main(String[] args) { 
    		Gson gson = new Gson();
    		model2 model2 = new model2("value24" , "value25");
    		model2 model3 = new model2("value34" , "value35");
    		ArrayList<model2> list3 = new ArrayList<model2>();
    		list3.add(model2);
    		list3.add(model3);
    		model model1 = new model("value1","value2","value3",list3);
    		String JsonMsg5 = gson.toJson(model1);
    		System.out.println("实体类嵌套另一个实体类list——转——json: " + JsonMsg5);
    		
    		model model7 = gson.fromJson(JsonMsg5, model.class);
    		System.out.println("json——转——实体类嵌套另一个实体类list: " + model7);
    	}

#### 结果： ####

实体类嵌套另一个实体类list——转——json: {"Name1":"value1","Name2":"value2","Name3":"value3","modelList":[{"Name4":"value24","Name5":"value25"},{"Name4":"value34","Name5":"value35"}]}
    json——转——实体类嵌套另一个实体类list: model [Name1=value1, Name2=value2, Name3=value3, modelList=[model2 [Name4=value4, Name5=value5], model2 [Name4=value64, Name5=value65]]]

## 总结： ##

#### 以上情况基本把java中会出现的json和实力类之间的转化解析都包含了，根据不同的接口需求进行修改即可，可以改更json的工具类。 ####