实现滚动条的自动滚动到textarea末尾的方法

textarea的滚动主要是用到一个

jScrollPane1.getViewport().setViewPosition(new Point(0,0));//到顶

但是也有人会说用jTextArea2 .setCaretPosition(0);但是事实证明，它好像没有什么大的用处，也放是本人不会用吧!

下面是我用jbuilder做的一个程序，在jbuilder6.0+win2000+jdk1.4能运行。

import javax.swing.*;

import java.awt.*;

import java.awt.event.*;

/**

* <p>Title: This follow is newman's writing</p>

* <p>Description: I want better writing ,instead of best one!</p>

* <p>Copyright: Copyright (c) 2002</p>

* <p>Company: newman0708@eastday.com</p>

* @author Newman

* @version 1.0

*/

public class ScrollFrame extends JFrame{

JPanel jPanel1 = new JPanel();

JScrollPane jScrollPane1 = new JScrollPane();

BorderLayout borderLayout1 = new BorderLayout();

JTextArea jTextArea1 = new JTextArea();

JPanel jPanel2 = new JPanel();

String str="gsdklfsdljfsdlkjfdsljfdslkfjslk/n"+

"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds/n"+

"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds/n"+

"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds/n"+

"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds/n"+

"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds/n"+

"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds/n"+

"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds/n"+

"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds/n"+

"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds/n"+

"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds/n"+

"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds/n"+

"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds/n"+

"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds/n"+

"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds/n"+

"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds/n"+

"sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfsdds/n"+

"end sdfjsdkfjsdlkjfkssdjfkdsfjdksjfksdsdfdssdfs/n";

JButton jButton1 = new JButton();

JButton jButton2 = new JButton();

public ScrollFrame() {

try {

jbInit();

}

catch(Exception e) {

e.printStackTrace();

}

}

public static void main(String[] args) {

ScrollFrame scrollFrame1 = new ScrollFrame();

scrollFrame1.setSize(200,300);

scrollFrame1.show();

}

private void jbInit() throws Exception {

this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE );

jPanel1.setLayout(borderLayout1);

jTextArea1.setText(this.str );

jScrollPane1.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);

jScrollPane1.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);

jButton1.setText("end");

jButton1.addActionListener(new java.awt.event.ActionListener() {

public void actionPerformed(ActionEvent e) {

jButton1_actionPerformed(e);

}

});

jButton2.setText("start");

jButton2.addActionListener(new java.awt.event.ActionListener() {

public void actionPerformed(ActionEvent e) {

jButton2_actionPerformed(e);

}

});

this.getContentPane().add(jPanel1, BorderLayout.CENTER);

jPanel1.add(jScrollPane1, BorderLayout.CENTER);

jPanel1.add(jPanel2, BorderLayout.SOUTH);

jPanel2.add(jButton1, null);

jPanel2.add(jButton2, null);

jScrollPane1.getViewport().add(jTextArea1, null);

}

void jButton1_actionPerformed(ActionEvent e) {//end

int height=10;

Point p = new Point();

p.setLocation(0,this.jTextArea1.getLineCount()*height);

this.jScrollPane1.getViewport().setViewPosition(p);

}

void jButton2_actionPerformed(ActionEvent e) {//start

Point p = new Point(0,0);

this.jScrollPane1.getViewport().setViewPosition(p);

}

}

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