Java实现生成JSON字符串的三种方式分享

// 演示数据
String code = "NOT_INITIALIZED";
String message = "Please initialize library";

char c1 = 'c';
String s1 = "s1";
System.out.println("{" + "\"c1\":" + "\"" + c1 + "\"" + "}");
System.out.println("{" + "\"s1\":" + "\"" + s1 + "\"" + "}");

boolean b1 = true;
float f1 = 34f;
double d1 = 33.2d;
System.out.println("{" + "\"b1\":" + b1 + "}");
System.out.println("{" + "\"f1\":" + f1 + "}");
System.out.println("{" + "\"d1\":" + d1 + "}");

String jsonStr = "{" + "\"code\":" + "\"" + code + "\"" + "," + "\"message\":" + "\"" + message + "\"" + "}";

class ErrorInfo {
    private String code;
    private String message;

    public String getCode() {
        return code;
    }

    public void setCode(String code) {
        this.code = code;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }
}

import com.google.gson.Gson;
ErrorInfo errorInfo = new ErrorInfo();
errorInfo.setCode(code);
errorInfo.setMessage(message);
Gson gson = new Gson();
String jsonStr = gson.toJson(errorInfo);

import org.json.JSONObject;
JSONObject jsonObject = new JSONObject();
String jsonStr = "";
try {
    jsonObject.put("code", code);
    jsonObject.put("message", message);
    jsonStr = jsonObject.toString();
} catch (JSONException e) {
    throw new RuntimeException(e);
}

HashMap<String, String> map = new HashMap<>();
map.put("code", code);
map.put("message", message);
String jsonStr = new JSONObject(map).toString();