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

package mangues.base;

import java.io.IOException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import mangues.model.Student;

/**
 * 
 * @ClassName: BaseServlet
 * @Description: 自定义servlet基类，实现参数的映射
 * @author mangues
 * @date 2015-7-21
 */
public abstract class BaseServlet extends HttpServlet {
    private List<String> var = null; // 存储字段名
    private List<String> vars = null; // 存储字段名
    private List<Method> ms = null; // 方法

    @Override
    public void init() throws ServletException {
        super.init();
        getVar();
    }

    // 是否自定义变量
    private boolean isParameter(String mName) {
        String con[] = { "getServletContext", "getServletConfig",
                "getServletName", "getInitParameter", "getInitParameterNames",
                "getServletInfo" };
        if (mName.startsWith("set") && !mName.startsWith("getClass")) {
            for (String nameString : con) {
                if (mName.equals(nameString)) {
                    return false;
                }
            }
            return true;
        } else {
            return false;
        }

    }
   //初始化
    private void getVar() {
        var = new ArrayList<String>();
        vars = new ArrayList<String>();
        ms = new ArrayList<Method>();
        Class classType = this.getClass();
        Method method[] = classType.getMethods();
        for (Method m : method) { // 遍历方法
            String mName = m.getName(); // 方法名
            if (isParameter(mName)) {
                try {
                    // 获取字段名
                    String fieldName = mName.substring(3, mName.length())
                            .toLowerCase();
                    vars.add(fieldName);
                    String ds = m.toString();
                    int i = ds.indexOf("(");
                    int j = ds.indexOf(")");
                    String str = ds.substring(i + 1, j);
                    var.add(str);
                    ms.add(m);
                } catch (Exception e) {
                    e.printStackTrace();
                }

            }
        }
    }

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request, response);
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        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
        for (int i = 0; i < vars.size(); i++) {
            String strs = vars.get(i); // 遍历出变量名
            String str = var.get(i); // 遍历出bean位置
            Method mehMethod = ms.get(i); // 方法
            String parameterKey;
            Class classType;
            try {
                classType = Class.forName(str);
                Object o = classType.newInstance();
                Method[] methods = classType.getMethods(); // 获取方法
                for (Method m : methods) { // 遍历方法
                    String mName = m.getName(); // 方法名
                    if (mName.startsWith("set")) {
                        // 获取字段名
                        String fieldName = mName.substring(3, mName.length())
                                .toLowerCase();
                        parameterKey = strs + "." + fieldName;
                        // 赋值
                        if (map.get(parameterKey) != null) {
                            String key[] = map.get(parameterKey);
                            String ds = m.toString();
                            int i1 = ds.indexOf("(");
                            int j1 = ds.indexOf(")");
                            String str1 = ds.substring(i1 + 1, j1);
                            if (str1.equals("java.lang.Integer")
                                    || str1.equals("int")) {
                                // 如果是int类型
                                int ip = Integer.parseInt(key[0]);
                                m.invoke(o, ip);
                            } else {
                                m.invoke(o, key[0]);
                            }

                        }
                    }
                }
                if (o != null) {

                    mehMethod.invoke(this, o);
                }

            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

        manguesPost(request, response);
    }

    protected abstract void manguesPost(HttpServletRequest request,
            HttpServletResponse response);
}

 

 

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;
    }
    
    
}