java 获取request中json数据

功能简介：

        Java 从 HttpServletRequest 中获取前端传输过来的json数据

效果展示：

请求示例：

post: 127.0.0.1:8081/getRequestJson

{"messageHistory",[{"message":"123","time":"2023-03-22 10:00:00"}],"isContextChat":true}

代码示例：

@RequestMapping(value = "getRequestJson", method = RequestMethod.POST)
@ResponseBody
public String getRequestJson(HttpServletRequest request) throws IOException {
    StringBuilder buffer = new StringBuilder();
    BufferedReader reader = request.getReader();
    String line;
    while ((line = reader.readLine()) != null) {
        buffer.append(line);
    }
    String requestBody = buffer.toString();
    System.out.println("--------> get request json is :" + requestBody);
	return requestBody;
}

拓展：

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;

@RequestMapping(value = "getRequestJson", method = RequestMethod.POST)
@ResponseBody
public String getRequestJson(HttpServletRequest request) throws IOException {

	// 1. 从HttpServletRequest对象中获取输入流，并读取请求正文。
	StringBuilder buffer = new StringBuilder();
	BufferedReader reader = request.getReader();
	String line;
	while ((line = reader.readLine()) != null) {
		buffer.append(line);
	}
	String requestBody = buffer.toString();

	// 2. 使用JSON库（如Jackson、Gson等）将字符串解析为JsonNode或任何其他适合你的数据结构。
	ObjectMapper mapper = new ObjectMapper(); // Jackson JSON库示例
	JsonNode jsonNode = mapper.readTree(requestBody); // 解析为JsonNode对象

	// 3. 现在，你可以使用jsonNode对象来访问和操作JSON数据了。
	String name = jsonNode.get("name").asText();
	int age = jsonNode.get("age").asInt();
	// 遍历所有属性并打印它们的值：
	Iterator<String> fieldNamesIter= jsonNode.fieldNames();
	while (fieldNamesIter.hasNext()){
		String fieldName=fieldNamesIter.next();
		JsonNode fieldValue=jsonNode.get(fieldName);
		System.out.println(fieldName+": "+fieldValue.asText());
	}

	System.out.println("--------> get request json is :" + requestBody);
	return requestBody;
}