利用java类的反射机制，实现了 映射 获得post（get）的参数 的BaseServlet

这几天一直在研究java的反射机制，正好作业需要写servlet，为了增加一点难度，就用java的反射机制来映射获取前端post或get过来的参数

 

1.该方式有点像struts2 利用映射获取前端的参数，目前只能映射javabean的Integer，String两种类型。有兴趣的同学可以自行添加别的类的判断

直接上代码，映射方式被我封装成了一个BaseServlet

 

2.直接用get方式访问http://localhost:8080/webTest/query?student.sname=1&student.sage=12      

   参数可以缺省，也可以利用post方式，这边为方便调用，就只用了get

 

3.得到的结果

1 package mangues.base;
2
3 import java.io.IOException;
4 import java.lang.reflect.Method;
5 import java.util.ArrayList;
6 import java.util.List;
7 import java.util.Map;
8 import javax.servlet.ServletException;
9 import javax.servlet.annotation.WebServlet;
10 import javax.servlet.http.HttpServlet;
11 import javax.servlet.http.HttpServletRequest;
12 import javax.servlet.http.HttpServletResponse;
13 import mangues.model.Student;
14
15 /**
16  *
17  * @ClassName: BaseServlet
18  * @Description: 自定义servlet基类，实现参数的映射
19  * @author mangues
20  * @date 2015-7-21
21  */
22 public abstract class BaseServlet extends HttpServlet {
23     private List<String> var = null; // 存储字段名
24     private List<String> vars = null; // 存储字段名
25     private List<Method> ms = null; // 方法
26
27     @Override
28     public void init() throws ServletException {
29         super.init();
30         getVar();
31     }
32
33     // 是否自定义变量
34     private boolean isParameter(String mName) {
35         String con[] = { "getServletContext", "getServletConfig",
36                 "getServletName", "getInitParameter", "getInitParameterNames",
37                 "getServletInfo" };
38         if (mName.startsWith("set") && !mName.startsWith("getClass")) {
39             for (String nameString : con) {
40                 if (mName.equals(nameString)) {
41                     return false;
42                 }
43             }
44             return true;
45         } else {
46             return false;
47         }
48
49     }
50    //初始化
51     private void getVar() {
52         var = new ArrayList<String>();
53         vars = new ArrayList<String>();
54         ms = new ArrayList<Method>();
55         Class classType = this.getClass();
56         Method method[] = classType.getMethods();
57         for (Method m : method) { // 遍历方法
58             String mName = m.getName(); // 方法名
59             if (isParameter(mName)) {
60                 try {
61                     // 获取字段名
62                     String fieldName = mName.substring(3, mName.length())
63                             .toLowerCase();
64                     vars.add(fieldName);
65                     String ds = m.toString();
66                     int i = ds.indexOf("(");
67                     int j = ds.indexOf(")");
68                     String str = ds.substring(i + 1, j);
69                     var.add(str);
70                     ms.add(m);
71                 } catch (Exception e) {
72                     e.printStackTrace();
73                 }
74
75             }
76         }
77     }
78
79     public void doGet(HttpServletRequest request, HttpServletResponse response)
80             throws ServletException, IOException {
81         doPost(request, response);
82     }
83
84     public void doPost(HttpServletRequest request, HttpServletResponse response)
85             throws ServletException, IOException {
86         request.setCharacterEncoding("utf-8");
87         response.setCharacterEncoding("utf-8");
88         Map<String, String[]> map = request.getParameterMap(); // 这个方法是获取用户请求时携带的参数名称和参数值，并将其组装成一个Map对象
89         for (int i = 0; i < vars.size(); i++) {
90             String strs = vars.get(i); // 遍历出变量名
91             String str = var.get(i); // 遍历出bean位置
92             Method mehMethod = ms.get(i); // 方法
93             String parameterKey;
94             Class classType;
95             try {
96                 classType = Class.forName(str);
97                 Object o = classType.newInstance();
98                 Method[] methods = classType.getMethods(); // 获取方法
99                 for (Method m : methods) { // 遍历方法
100                     String mName = m.getName(); // 方法名
101                     if (mName.startsWith("set")) {
102                         // 获取字段名
103                         String fieldName = mName.substring(3, mName.length())
104                                 .toLowerCase();
105                         parameterKey = strs + "." + fieldName;
106                         // 赋值
107                         if (map.get(parameterKey) != null) {
108                             String key[] = map.get(parameterKey);
109                             String ds = m.toString();
110                             int i1 = ds.indexOf("(");
111                             int j1 = ds.indexOf(")");
112                             String str1 = ds.substring(i1 + 1, j1);
113                             if (str1.equals("java.lang.Integer")
114                                     || str1.equals("int")) {
115                                 // 如果是int类型
116                                 int ip = Integer.parseInt(key[0]);
117                                 m.invoke(o, ip);
118                             } else {
119                                 m.invoke(o, key[0]);
120                             }
121
122                         }
123                     }
124                 }
125                 if (o != null) {
126
127                     mehMethod.invoke(this, o);
128                 }
129
130             } catch (Exception e) {
131                 // TODO Auto-generated catch block
132                 e.printStackTrace();
133             }
134         }
135
136         manguesPost(request, response);
137     }
138
139     protected abstract void manguesPost(HttpServletRequest request,
140             HttpServletResponse response);
141 }

 

 

下面是 一个简单的继承servlet，只需要利用get方式访问

package mangues.servlet;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import mangues.base.BaseServlet;
import mangues.model.Student;

@WebServlet(urlPatterns = { "/query" })
public class AddServlet extends BaseServlet {
private Student student;
public Student getStudent() {
return student;
}
public void setStudent(Student student) {
this.student = student;
}

@Override
protected void manguesPost(HttpServletRequest request,
HttpServletResponse response) {
System.out.println(student.getSname());
}

}

 

 

下面是需要映射的Bean

package mangues.model;

public class Student {
private String sno; //学号
private String sname;//姓名
private Integer sage; //年龄
private String ssex; //性别
public Student() {
super();
}
public Student(String sno, String sname, Integer sage, String ssex) {
super();
this.sno = sno;
this.sname = sname;
this.sage = sage;
this.ssex = ssex;
}
public String getSno() {
return sno;
}
public void setSno(String sno) {
this.sno = sno;
}
public String getSname() {
return sname;
}
public void setSname(String sname) {
this.sname = sname;
}
public Integer getSage() {
return sage;
}
public void setSage(Integer sage) {
this.sage = sage;
}
public String getSsex() {
return ssex;
}
public void setSsex(String ssex) {
this.ssex = ssex;
}

}