测试Java反射效率

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测试分为3个方面：1. 实例化效率；2. 方法调用效率；3. 成员变量GET调用效率；4. 成员变量SET调用

测试环境：

Windows 7

Sun Java 1.6

先写好备测试用的类

import java.util.Date;

public class DemoClass{
public String firstName;
private String endName;
private Date birthDay;
private String email;
private String phone;
private DemoClass parent;

public String getFirstName() {
    return firstName;
    }
public void setFirstName(String firstName) {
    this.firstName = firstName;
    }
public String getEndName() {
    return endName;
    }
public void setEndName(String endName) {
    this.endName = endName;
    }
public Date getBirthDay() {
    return birthDay;
    }
public void setBirthDay(Date birthDay) {
    this.birthDay = birthDay;
    }
public String getEmail() {
    return email;
    }
public void setEmail(String email) {
    this.email = email;
    }
public String getPhone() {
    return phone;
    }
public void setPhone(String phone) {
    this.phone = phone;
    }
public DemoClass getParent() {
    return parent;
    }
public void setParent(DemoClass parent) {
    this.parent = parent;
    }
}

1. 实例化效率

1) 正常调用

public class TestReflectNew {

public static void main(String[] args) throws Exception{

     int i = 0;
     long start = System.currentTimeMillis();
     while(i<1000000){
     i++;
//     DemoClass.class.newInstance();
     new DemoClass();
     }

     long end = System.currentTimeMillis();
     System.err.println((end - start) + " MillSeconds");
    }
}
三次输出：

18 MillSeconds

19 MillSeconds

20 MillSeconds

均值：19

2) 反射调用

public class TestReflectNew {

public static void main(String[] args) throws Exception{

     int i = 0;
     long start = System.currentTimeMillis();
     while(i<1000000){
     i++;
     DemoClass.class.newInstance();
//     new DemoClass();
     }

     long end = System.currentTimeMillis();
     System.err.println((end - start) + " MillSeconds");
    }
}
三次输出：

191 MillSeconds

193 MillSeconds
192 MillSeconds

均值：192

2. 方法调用测试

1) 正常调用

public class TestReflectMethod {

public static void main(String[] args) throws Exception{

     int i = 0;
     DemoClass dc = new DemoClass();
     long start = System.currentTimeMillis();
     while(i<1000000){
     i++;
//     DemoClass.class.getMethod("getBirthDay").invoke(dc);
     dc.getBirthDay();
     }

     long end = System.currentTimeMillis();
     System.err.println((end - start) + " MillSeconds");
    }
}

三次输出：

2 MillSeconds

均值：2

2) 反射调用

public class TestReflectMethod {

public static void main(String[] args) throws Exception{

     int i = 0;
     DemoClass dc = new DemoClass();
     long start = System.currentTimeMillis();
     while(i<1000000){
     i++;
     DemoClass.class.getMethod("getBirthDay").invoke(dc);
//     dc.getBirthDay();
     }

     long end = System.currentTimeMillis();
     System.err.println((end - start) + " MillSeconds");
    }
}

三次输出：

1223 MillSeconds

1201 MillSeconds

1207 MillSeconds

均值1210

3. 测试成员变量GET

1) 正常调用

public class TestReflectFieldGet {

public static void main(String[] args) throws Exception{

     int i = 0;
     DemoClass dc = new DemoClass();
     String s;
     long start = System.currentTimeMillis();
     while(i<1000000){
     i++;
//     s = (String) DemoClass.class.getField("firstName").get(dc);
     s = dc.firstName;
     }

     long end = System.currentTimeMillis();
     System.err.println((end - start) + " MillSeconds");
    }
}
三次输出：

2 MillSeconds

1 MillSeconds

3 MillSeconds

均值：2

2) 反射调用

public class TestReflectFieldGet {

public static void main(String[] args) throws Exception{

     int i = 0;
     DemoClass dc = new DemoClass();
     String s;
     long start = System.currentTimeMillis();
     while(i<1000000){
     i++;
     s = (String) DemoClass.class.getField("firstName").get(dc);
//     s = dc.firstName;
     }

     long end = System.currentTimeMillis();
     System.err.println((end - start) + " MillSeconds");
    }
}
三次输出：

992 MillSeconds

1000 MillSeconds

1005 MillSeconds

均值：999

4. 测试成员变量SET

1) 正常调用

public class TestReflectFieldSet {

public static void main(String[] args) throws Exception {

     int i = 0;
     DemoClass dc = new DemoClass();
     String s = null;
     long start = System.currentTimeMillis();
     while(i<1000000){
     i++;
     dc.firstName = s;
//     DemoClass.class.getField("firstName").set(dc, s);
     }

     long end = System.currentTimeMillis();
     System.err.println((end - start) + " MillSeconds");
    }
}

三次输出：

1 MillSeconds

2 MillSeconds

均值：1.7

2) 反射调用

public class TestReflectFieldSet {

public static void main(String[] args) throws Exception {

     int i = 0;
     DemoClass dc = new DemoClass();
     String s = null;
     long start = System.currentTimeMillis();
     while(i<1000000){
     i++;
//     dc.firstName = s;
     DemoClass.class.getField("firstName").set(dc, s);
     }

     long end = System.currentTimeMillis();
     System.err.println((end - start) + " MillSeconds");
    }
} 三次输出：

998 MillSeconds

1021 MillSeconds

1007 MillSeconds

均值：1009

来个统计

反射平均时间非反射平均时间比值
实例化 192 19 10
方法调用 1210 2 605
成员Get 999 2 500
成员Set 1009 1.7 593