前景介绍
在我们日常开发过程中，前台向后台传递参数一般是json 或者 form表单方式，并且最好统一一种传输方式，不建议json+form混合使用，但是由于form表单在数组结构下拼接比较麻烦，一般都采用的json去传递，后端采用SpringBoot（SpringMVC）一般使用@RequestBody注解去接收数据，但如下情况不太好处理
@RequestMapping("/login")
public String login(String name,String password){
....
}
复制代码以上方法如果去接收json对象是无法映射的，由于字段太少封装成对象+@RequestBody又太过于繁琐， 这种情况我们可以使用自定义注解+方法参数解析器去解决这个问题
一.导入相关依赖
框架中是用的hutool工具包，根据自己项目情况使用json序列化工具
<dependency>
<groupId>cn.hutool</groupId>
<artifactId>hutool-all</artifactId>
<version>5.7.6</version>
</dependency>
复制代码二.定义注解
通过自定义注解标注在需要做数据映射的参数上
@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface JSONParameter {
@AliasFor("name")
String value() default "";
@AliasFor("value")
String name() default "";
boolean required() default false;
String defaultValue() default "";
}
复制代码三.编写自定义参数解析器
package com.gosun.swd.commom.resolver;
import cn.hutool.json.JSONArray;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.gosun.swd.commom.annotation.JSONParameter;
import com.gosun.swd.commom.exception.Assert;
import org.springframework.core.MethodParameter;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.ModelAndViewContainer;
import sun.reflect.generics.reflectiveObjects.ParameterizedTypeImpl;
import javax.servlet.http.HttpServletRequest;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Type;
import java.util.List;
import java.util.Set;
@Component
public class JSONParameterResolver implements HandlerMethodArgumentResolver {
// ThreadLocal<JSONObject> paramObject = new ThreadLocal<>();
@Override
public boolean supportsParameter(MethodParameter methodParameter) {
return methodParameter.hasParameterAnnotation(JSONParameter.class);
}
@Override
public Object resolveArgument(MethodParameter methodParameter, ModelAndViewContainer modelAndViewContainer, NativeWebRequest nativeWebRequest, WebDataBinderFactory webDataBinderFactory) throws Exception {
JSONObject jsonObject = getJsonObject();
Object o = jsonObject.get(methodParameter.getParameterName());
JSONParameter parameterAnnotation = methodParameter.getParameterAnnotation(JSONParameter.class);
//判断是否允许为空
String message = String.format("参数%s不能为空", methodParameter.getParameterName());
Assert.assertFalse(parameterAnnotation.required() && o == null, message);
//如果为空设置默认值
if (o == null) {
return convertParameter(methodParameter, parameterAnnotation.defaultValue());
}
return convertParameter(methodParameter, o);
}
private Object convertParameter(MethodParameter methodParameter, Object o) throws ClassNotFoundException, InstantiationException, IllegalAccessException, InvocationTargetException {
if (methodParameter.getParameterType().getTypeName().equals(List.class.getTypeName()) ||
methodParameter.getParameterType().getTypeName().equals(Set.class.getTypeName())) {
Type actualTypeArgument = ((ParameterizedTypeImpl) methodParameter.getGenericParameterType()).getActualTypeArguments()[0];
return JSONUtil.toList((JSONArray) o, Class.forName(actualTypeArgument.getTypeName()));
} else {
return convertParameter(methodParameter, String.valueOf(o));
}
}
private Object convertParameter(MethodParameter methodParameter, String obj) throws InstantiationException, IllegalAccessException, InvocationTargetException {
Constructor<?>[] constructors = methodParameter.getParameterType().getConstructors();
for (Constructor<?> constructor : constructors) {
if (constructor.getParameterCount() == 1 && constructor.getParameters()[0].getParameterizedType().getTypeName().equals(String.class.getTypeName())) {
return constructor.newInstance(obj);
}
}
return null;
}
private JSONObject getJsonObject() throws IOException {
HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest();
BufferedReader streamReader = new BufferedReader(new InputStreamReader(request.getInputStream(), "UTF-8"));
StringBuilder responseStrBuilder = new StringBuilder();
String inputStr;
while ((inputStr = streamReader.readLine()) != null) {
responseStrBuilder.append(inputStr);
}
String jsonStr = responseStrBuilder.toString();
// if (StringUtils.isEmpty(jsonStr)) {//如果没有参数，表示不是第一次进入
// return paramObject.get() == null ? new JSONObject() : paramObject.get();
// }
JSONObject jsonObject = JSONUtil.parseObj(jsonStr);
// paramObject.set(jsonObject);
return jsonObject;
}
}
复制代码四.解决二次获取request信息丢失的问题
1.编写过滤器
package com.gosun.swd.commom.resolver;
import org.springframework.stereotype.Component;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
/**
* @author:
*/
@Component
@WebFilter(filterName = "channelFilter", urlPatterns = {"/*"})
public class ChannelFilter implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) {
try {
ServletRequest requestWrapper = null;
if (request instanceof HttpServletRequest) {
requestWrapper = new RequestWrapper((HttpServletRequest) request);
}
if (requestWrapper == null) {
chain.doFilter(request, response);
} else {
chain.doFilter(requestWrapper, response);
}
} catch (IOException e) {
e.printStackTrace();
} catch (ServletException e) {
e.printStackTrace();
}
}
@Override
public void destroy() {
}
}
复制代码2.编写构造器
package com.gosun.swd.commom.resolver;
import org.apache.commons.io.IOUtils;
import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.*;
/**
* @author:
*/
public class RequestWrapper extends HttpServletRequestWrapper {
//参数字节数组
private byte[] requestBody;
//Http请求对象
private HttpServletRequest request;
public RequestWrapper(HttpServletRequest request) throws IOException {
super(request);
this.request = request;
}
/**
* @return
* @throws IOException
*/
@Override
public ServletInputStream getInputStream() throws IOException {
/**
* 每次调用此方法时将数据流中的数据读取出来，然后再回填到InputStream之中
* 解决通过@RequestBody和@RequestParam（POST方式）读取一次后控制器拿不到参数问题
*/
if (null == this.requestBody) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
IOUtils.copy(request.getInputStream(), baos);
this.requestBody = baos.toByteArray();
}
final ByteArrayInputStream bais = new ByteArrayInputStream(requestBody);
return new ServletInputStream() {
@Override
public boolean isFinished() {
return false;
}
@Override
public boolean isReady() {
return false;
}
@Override
public void setReadListener(ReadListener listener) {
}
@Override
public int read() {
return bais.read();
}
};
}
public byte[] getRequestBody() {
return requestBody;
}
@Override
public BufferedReader getReader() throws IOException {
return new BufferedReader(new InputStreamReader(this.getInputStream()));
}
}
复制代码五.调用实例代码
@RequestMapping("/login")
public String login(@JSONParameter String name, @JSONParameter String password){
....
}
//包含默认值的参数映射
@PostMapping(value = "/getEvents", consumes = "application/json")
public ResultVo<Events> getEvents(@JSONParameter(name = "page", defaultValue = "1") Long page,
@RequestParam(name = "per_page", defaultValue = "10") Long per_page,
@JSONParameter String type) {
....
}
//字段集合
@PostMapping(value = "/deleteCarInfo", consumes = "application/json")
public ResultVo deleteCarInfo(@JSONParameter List<Long> ids) {
....
}
复制代码