设计模式之模板模式(Template Model)
模板模式即设定一个模板类，执行的子类继承这个抽象类，实现具体的方法。用于不同实现类拥有相同的执行方法模式，只是内容不一样，但是执行的步骤是完全一样的，这也就是为什么可以用抽象类作为父类。
代码如下：
package TemplatedMethod;
public abstract class AbstractRead {
protected String resource;
public void getContent() { // Template Method
if(open()) {
readContent();
close();
}
}
public void setResource(String s) {
resource = s;
}
protected abstract boolean open();
protected abstract void readContent();
protected abstract void close();
}
package TemplatedMethod;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
public class ReadFile extends AbstractRead {
private BufferedReader in = null;
public ReadFile() {
}
public ReadFile(String fileName) {
resource = fileName;
}
protected boolean open() {
try {
in = new BufferedReader(new FileReader(resource));
} catch(IOException e) {
System.out.println("Can not open file!");
return false;
}
return true;
}
protected void readContent() {
try {
if(in != null) {
String str;
while((str = in.readLine()) != null) {
System.out.println(str);
}
}
} catch(IOException e) {
System.out.println("Read file error !");
}
}
protected void close() {
if(in != null) {
try {
in.close();
} catch(IOException e) {
System.out.println("IO error !");
}
}
}
}
package TemplatedMethod;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
public class ReadHtml extends AbstractRead {
private URLConnection conn;
private BufferedReader in;
public ReadHtml() {
}
public ReadHtml(String s) {
resource = s;
}
public boolean open() {
try {
URL url = new URL(resource);
conn = url.openConnection();
in = new BufferedReader (
new InputStreamReader(conn.getInputStream()));
} catch (MalformedURLException e) {
System.out.println("Uable to connect URL:" + resource);
return false;
} catch (IOException e) {
System.out.println("IOExeption when connecting to URL" + resource);
return false;
}
return true;
}
protected void readContent() {
try {
if(in != null) {
String str;
while((str = in.readLine()) != null) {
System.out.println(str);
}
}
} catch(IOException e) {
System.out.println("Read file error !");
}
}
@Override
protected void close() {
// TODO Auto-generated method stub
}
}
package TemplatedMethod;
public class Test {
public static void main(String[] args) {
// You should change the path of "test.txt" in your local machine
String fileName = "D:\\项目参考资料\\book\\java\\23 design model\\templatemethod.txt";
String url = "http://www.the9.com/main.htm";
AbstractRead fileRead = new ReadFile();
AbstractRead htmlRead = new ReadHtml();
fileRead.setResource(fileName);
htmlRead.setResource(url);
System.out.println("----- Read from a file -----");
fileRead.getContent();
System.out.println("----- Read from a url -----");
htmlRead.getContent();
}
}
输出：
----- Read from a file -----
/**
* An abstract class which can get content from a file or a HTTP URL
* or other resource
*/
public abstract class AbstractRead {
protected String resource;
public void getContent() { // Template Method
if(open()) {
readContent();
close();
}
}
public void setResource(String s) {
resource = s;
}
protected abstract boolean open();
protected abstract void readContent();
protected abstract void close();
}
public class ReadFile extends AbstractRead {
private BufferedReader in = null;
public ReadFile() {
}
public ReadFile(String fileName) {
resource = fileName;
}
protected boolean open() {
try {
in = new BufferedReader(new FileReader(resource));
} catch(IOException e) {
System.out.println("Can not open file!");
return false;
}
return true;
}
protected void readContent() {
try {
if(in != null) {
String str;
while((str = in.readLine()) != null) {
System.out.println(str);
}
}
} catch(IOException e) {
System.out.println("Read file error !");
}
}
protected void close() {
if(in != null) {
try {
in.close();
} catch(IOException e) {
System.out.println("IO error !");
}
}
}
}
public class ReadHtml extends AbstractRead {
private URLConnection conn;
private BufferedReader in;
public ReadHtml() {
}
public ReadHtml(String s) {
resource = s;
}
public boolean open() {
try {
URL url = new URL(resource);
conn = url.openConnection();
in = new BufferedReader (
new InputStreamReader(conn.getInputStream()));
} catch (MalformedURLException e) {
System.out.println("Uable to connect URL:" + resource);
return false;
} catch (IOException e) {
System.out.println("IOExeption when connecting to URL" + resource);
return false;
}
return true;
}
protected void readContent() {
try {
if(in != null) {
String str;
while((str = in.readLine()) != null) {
System.out.println(str);
}
}
} catch(IOException e) {
System.out.println("Read file error !");
}
public class Test {
public static void main(String[] args) {
// You should change the path of "test.txt" in your local machine
String fileName = "d:\\javaproject\\TemplateMethod\\src\\test.txt";
String url = "http://www.the9.com/main.htm";
AbstractRead fileRead = new ReadFile();
AbstractRead htmlRead = new ReadHtml();
fileRead.setResource(fileName);
htmlRead.setResource(url);
System.out.println("----- Read from a file -----");
fileRead.getContent();
System.out.println("----- Read from a url -----");
htmlRead.getContent();
}
}
----- Read from a url -----
<html><frameset> <frame id='top' src="http://172.16.100.250/disable/disable.htm"><noframes> <body>Your browse does not support frame!</body> </noframes> </frameset> </html>
