自己写了个小工具类，将Servlet里面的HttpServletRequest请求封装成为一个POJO对象，可以复习一下Java的反射原理，开发中这个没什么用，毕竟都用MVC框架，框架都自带这种功能，而且更为强大，不过框架也应该是采用这种原理，通过这个也能对框架窥测一二。
这是工具类：通过传入POJO的Class对象来自动封装一个POJO。
package com.xxx.xxx.util; import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Enumeration; import javax.servlet.http.HttpServletRequest; public class PackObject<T> {
Class<T> c; public static <T> T getObject(HttpServletRequest request, Class<T> c) { T t = null;
try {
t = c.newInstance(); // 实例化参数对象
} catch (InstantiationException e1) {
e1.printStackTrace();
} catch (IllegalAccessException e1) {
e1.printStackTrace();
} @SuppressWarnings("rawtypes")
Enumeration e = request.getParameterNames(); // 所有请求参数 Method[] methods = c.getDeclaredMethods(); // 参数对象的所有方法 // 根据对象的set方法的参数类型去将请求的值做相应转换
while (e.hasMoreElements()) {
String paramName = e.nextElement().toString();
String setParamName = reverseParamName(paramName); //将参数名字转换成set方法名字，如：id 转换成 setId for (Method method : methods) {
if (setParamName.equals(method.getName())) {
try {
Class<?> paramType = (method.getParameterTypes())[0]; //得到set方法参数类型
String value = request.getParameter(paramName);
adapter(t, method, paramType, value); //通过适配器将值注入进POJO里面
} catch (IllegalArgumentException e1) {
e1.printStackTrace();
} catch (IllegalAccessException e1) {
e1.printStackTrace();
} catch (InvocationTargetException e1) {
e1.printStackTrace();
} catch (SecurityException e1) {
e1.printStackTrace();
}
}
}
}
return t;
} private static String reverseParamName(String paramName) {
char firstChar = paramName.charAt(0);
char toUpper = Character.toUpperCase(firstChar);
String setParamName = "set" + String.valueOf(toUpper)
+ paramName.substring(1);
return setParamName;
} private static <T> void adapter(T t, Method method, Class<?> paramType,
String value) throws IllegalAccessException,
InvocationTargetException {
if (paramType == String.class) {
method.invoke(t, value);
} else if (paramType == Integer.class || paramType == int.class) {
method.invoke(t, Integer.parseInt(value));
} else if (paramType == Long.class || paramType == long.class) {
method.invoke(t, Long.parseLong(value));
} else if (paramType == Boolean.class || paramType == boolean.class) {
method.invoke(t, Boolean.parseBoolean(value));
} else if (paramType == Short.class || paramType == short.class) {
method.invoke(t, Short.parseShort(value));
} else if (paramType == Float.class || paramType == float.class) {
method.invoke(t, Float.parseFloat(value));
} else if (paramType == Double.class || paramType == double.class) {
method.invoke(t, Double.parseDouble(value));
} else if (paramType == Character.class || paramType == char.class) {
char[] cs = value.toCharArray();
if (cs.length > 1) {
throw new IllegalArgumentException("参数长度太大");
}
method.invoke(t, value.toCharArray()[0]);
}
}
}
POJO类：
package com.xxx.xxx.util;
public class User {
private int id;
private String name;
private String password;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
@Override
public String toString() {
return "User [id=" + id + ", name=" + name + ", password=" + password
+ "]";
}
}
Servlet：
package com.xxx.xxx.util; import java.io.IOException; import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse; @SuppressWarnings("serial")
@WebServlet("/UserServlet")
public class UserServlet extends HttpServlet { protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
User user = PackObject.getObject(request, User.class);
System.out.println(user);
} protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
} }
页面：分别输入id：123，name：Jay，password：Jolin
<form action="UserServlet">
id:<input name="id" /><br />
name:<input name="name" /><br />
password:<input name="password" type="password" /><br />
<input type="submit" value="submit" />
</form>
结果：User [id=123, name=Jay, password=Jolin]
只测了下int类型和String类型没有问题，没什么问题。