caread.java

读出数字证书的内容,能通过程序读出有关此证书的相关信息

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.table.*;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;
import java.io.*;
public class CARead extends JPanel {
private String CA_Name; 
private String CA_ItemData[][] = new String[9][2];
private String[] columnNames = {"证书字段标记","内容" };
public CARead(String CertName) {
CA_Name=CertName;
/* 三个Panel用来显示证书内容*/
JTabbedPane tabbedPane = new JTabbedPane();
JPanel panelNormal = new JPanel();
tabbedPane.addTab("普通信息", panelNormal); 
JPanel panelAll=new JPanel();
panelAll.setLayout(new BorderLayout());
tabbedPane.addTab("所有信息",panelAll);
JPanel panelBase64=new JPanel();
panelBase64.setLayout(new BorderLayout());
tabbedPane.addTab("Base64编码信息",panelBase64);
/* 读取证书常规信息 */
Read_Normal(panelNormal);
/* 读取证书文件字符串表示内容 */
Read_Bin(panelAll);
/* 读取证原始Base64编码形式的证书文件 */
Read_Raw(panelBase64);
tabbedPane.setSelectedIndex(0);
setLayout(new GridLayout(1, 1)); 
add(tabbedPane);
}
/*以下是定义的Read_Normal()，Read_Bin(),Read_Raw()以及main() 
这里省略... */ 
}
/*定义证书信息的读取函数如下： */
private int Read_Normal(JPanel panel){
String Field;
try{
CertificateFactory certificate_factory=CertificateFactory.getInstance("X.509");
FileInputStream file_inputstream=new FileInputStream(CA_Name);
X509Certificate 
x509certificate=(X509Certificate)certificate_factory.generateCertificate
(file_inputstream);
Field=x509certificate.getType();
CA_ItemData[0][0]="类型";
CA_ItemData[0][1]=Field;
Field=Integer.toString(x509certificate.getVersion());
CA_ItemData[1][0]="版本";
CA_ItemData[1][1]=Field; 
Field=x509certificate.getSubjectDN().getName();
CA_ItemData[2][0]="标题";
CA_ItemData[2][1]=Field;
/* 以下类似，这里省略 
Field=x509certificate.getNotBefore().toString();得到开始有效日期
Field=x509certificate. getNotAfter().toString();得到截止日期
Field=x509certificate.getSerialNumber().toString(16);得到序列号
Field=x509certificate.getIssuerDN().getName();得到发行者名
Field=x509certificate.getSigAlgName();得到签名算法
Field=x509certificate.getPublicKey().getAlgorithm();得到公钥算法 */
file_inputstream.close();
final JTable table = new JTable(CA_ItemData, columnNames);
TableColumn tc=null;
tc = table.getColumnModel().getColumn(1);
tc.setPreferredWidth(600); 
panel.add(table);
}catch(Exception exception){
exception.printStackTrace();
return -1;
}
return 0;
}
/*如果以字符串形式读取证书，加入下面Read_Bin这个函数。其中CertificateFactory.generateCertificate() 这个函数可以从证书标准编码(RFC1421定义)中解出可读信息。Read_Bin函数代码如下： 
*/
private int Read_Bin(JPanel panel){
try{
FileInputStream file_inputstream=new FileInputStream(CA_Name);
DataInputStream data_inputstream=new DataInputStream(file_inputstream);
CertificateFactory certificatefactory=CertificateFactory.getInstance("X.509");
byte[] bytes=new byte[data_inputstream.available()];
data_inputstream.readFully(bytes);
ByteArrayInputStream bais=new ByteArrayInputStream(bytes);
JEditorPane Cert_EditorPane;
Cert_EditorPane=new JEditorPane();
while(bais.available()>0){
X509Certificate 
Cert=(X509Certificate)certificatefactory.generateCertificate(bais);
Cert_EditorPane.setText(Cert_EditorPane.getText()+Cert.toString());
}
Cert_EditorPane.disable();
JScrollPane edit_scroll=new JScrollPane(Cert_EditorPane);
panel.add(edit_scroll);
file_inputstream.close();
data_inputstream.close();
}catch( Exception exception){
exception.printStackTrace();
return -1;
}
return 0; 
}
/*如果要得到原始证书编码后的信息，则可用如下代码： */

private int Read_Raw(JPanel panel){
try{ 
JEditorPane Cert_EditorPane=new JEditorPane();
String CertText=null;
File inputFile = new File(CA_Name);
FileReader in = new FileReader(inputFile);
char[] buf=new char[2000];
int len=in.read(buf,0,2000);
for(int i=1;i<len;i++) 
{ 
CertText=CertText+buf[i];
}
in.close();
Cert_EditorPane.setText(CertText);
Cert_EditorPane.disable();
JScrollPane edit_scroll=new JScrollPane(Cert_EditorPane);
panel.add(edit_scroll);
}catch( Exception exception){
exception.printStackTrace();
return -1;
}
return 0; 
}
/*最后用这个小程序看一看刚才生成的证书mycert.crt内容，把文件名写入main()中：*/ 
public static void main(String[] args) {
JFrame frame = new JFrame("证书阅读器");
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {System.exit(0);}
});
frame.getContentPane().add(new CARead("mycert.crt"),BorderLayout.CENTER);
frame.setSize(700, 425);
frame.setVisible(true);
}