qingqing3721

import java.util.zip.*; import
java.io.*; public class ZipIt {
public static void main(String args[]) throws IOException
{ if (args.length  
2) {
System.err.println("usage: java ZipIt Zip.zip file1 file2 file3");
System.exit
(-1); }
File zipFile = new File(args
[0]); if
(zipFile.exists()) {
System.err.println("Zip file already exists, please try another");
System.exit
(-2); }
FileOutputStream fos = new
FileOutputStream(zipFile);
ZipOutputStream zos = new
ZipOutputStream(fos); int bytesRead; byte[]
buffer = new byte[1024]; CRC32 crc = new CRC32(); for (int i=1, n=args.length; i  n; i++) {
String name
= args;
File file =
new File(name);
if (!
file.exists()) {

nbsp; System.err.println("Skipping: " + name);

nbsp; continue;
}
BufferedInputStream bis = new BufferedInputStream(

nbsp; new FileInputStream(file));
crc.reset
();
while
((bytesRead = bis.read(buffer)) != -1) {

nbsp; crc.update(buffer, 0, bytesRead);
}
bis.close();
// Reset to
beginning of input stream
bis = new
BufferedInputStream(

nbsp; new FileInputStream(file));
ZipEntry
entry = new ZipEntry(name);
entry.setMethod(ZipEntry.STORED);
entry.setCompressedSize(file.length());
entry.setSize(file.length());
entry.setCrc(crc.getValue());
zos.putNextEntry(entry);
while
((bytesRead = bis.read(buffer)) != -1) {

nbsp; zos.write(buffer, 0, bytesRead);
}
bis.close(); }
zos.close
(); } } import java.util.zip.*;import java.io.*;public class ZipIt {public static void main(String args
[]) throws IOException {if
(args.length  2)
{System.err.println("usage: java ZipIt Zip.zip file1 file2
file3");System.exit(-1);}
File zipFile = new File(args
[0]);if (zipFile.exists())
{System.err.println("Zip file already exists, please try
another");System.exit(-2);}
FileOutputStream fos = new
FileOutputStream(zipFile);ZipOutputStream zos = new ZipOutputStream
(fos);int
bytesRead;byte[] buffer = new byte
[1024];CRC32 crc = new CRC32
();for (int i=1, n=args.length; i
n; i++)
{String name
= args;File file = new File
(name);if
(!file.exists())
{ System.err.println("Skipping: " +
name);
nbsp;
continue;}
BufferedInputStream bis = new BufferedInputStream
( new FileInputStream
(file));crc.reset();while ((bytesRead = bis.read(buffer)) != -1)
{ crc.update(buffer, 0,
bytesRead);}bis.close
();// Reset
to beginning of input
streambis =
new BufferedInputStream
( new FileInputStream
(file));ZipEntry entry = new ZipEntry
(name);entry.setMethod
(ZipEntry.STORED);
nbsp; entry.setCompressedSize(file.length
());entry.setSize(file.length
());entry.setCrc(crc.getValue
());zos.putNextEntry
(entry);while ((bytesRead = bis.read(buffer)) != -1)
{ zos.write(buffer, 0,
bytesRead);}bis.close
();}
zos.close();}}16. Parsing / Reading XML file in JavaSample XML file.

John
B
12

Mary
A
11

Simon
A
18
JohnB12MaryA
AGE11SimonA18
Java code to parse above XML.package net.viralpatel.java.xmlparser; import java.io.File; import
javax.xml.parsers.DocumentBuilder; import
javax.xml.parsers.DocumentBuilderFactory; import
org.w3c.dom.Document; import org.w3c.dom.Element;
import org.w3c.dom.Node; import
org.w3c.dom.NodeList; public class XMLParser
{ public void getAllUserNames(String
fileName) { try
{
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
File file =
new File(fileName);
if
(file.exists()) {

nbsp; Document doc = db.parse(file);

nbsp; Element docEle = doc.getDocumentElement();
nbsp; // Print root element of the document

nbsp; System.out.println("Root element of the document: "

nbsp; + docEle.getNodeName
());
nbsp; NodeList studentList = docEle.getElementsByTagName
("student");
nbsp; // Print total student elements in document

nbsp; System.out

nbsp; .println("Total
students: " + studentList.getLength());
nbsp; if (studentList != null  studentList.getLength()  0)
{

nbsp; for (int i = 0; i  studentList.getLength();
i++) {
nbsp; Node node =
studentList.item(i);
nbsp; if (node.getNodeType()
== Node.ELEMENT_NODE) {
nbsp;
System.out

nbsp;
.println
("=====================");
nbsp;
Element e = (Element) node;

nbsp;
NodeList nodeList = e.getElementsByTagName("name");

nbsp;
System.out.println("Name: "

nbsp;
+ nodeList.item(0).getChildNodes
().item(0)

nbsp;

; .getNodeValue());
nbsp;
nodeList = e.getElementsByTagName("grade");

nbsp;
System.out.println("Grade: "

nbsp;
+ nodeList.item(0).getChildNodes
().item(0)

nbsp;

; .getNodeValue());
nbsp;
nodeList = e.getElementsByTagName("age");

nbsp;
System.out.println("Age: "

nbsp;
+ nodeList.item(0).getChildNodes
().item(0)

nbsp;

; .getNodeValue());

nbsp; }

nbsp; }

nbsp; } else {

nbsp; System.exit(1);

nbsp; }
}
} catch (Exception e)
{
System.out.println(e); } } public
static void main(String[] args) { XMLParser parser = new XMLParser
(); parser.getAllUserNames("c:\\test.xml"); }
} package net.viralpatel.java.xmlparser;import java.io.File;import javax.xml.parsers.DocumentBuilder;import
javax.xml.parsers.DocumentBuilderFactory;import org.w3c.dom.Document;import org.w3c.dom.Element;import
org.w3c.dom.Node;import org.w3c.dom.NodeList;public class XMLParser {public void getAllUserNames(String fileName) {try
{DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();DocumentBuilder db =
dbf.newDocumentBuilder();File file = new File
(fileName);if (file.exists())
{Document doc = db.parse
(file);Element docEle = doc.getDocumentElement();// Print root element of the
documentSystem.out.println("Root element of the
document: "+ docEle.getNodeName());NodeList studentList = docEle.getElementsByTagName("student");// Print total student elements in
documentSystem.outnb
sp;.println("Total students: " + studentList.getLength());if (studentList != null  
studentList.getLength()  0) {for (int i = 0; i  
studentList.getLength(); i++) {Node node = studentList.item(i);if (node.getNodeType() == Node.ELEMENT_NODE) {System.out .println("=====================");Element e = (Element)
node;NodeList nodeList = e.getElementsByTagName
("name");System.out.println("Name:
"+ nodeList.item(0).getChildNodes().item(0)
.getNodeValue());nodeList = e.getElementsByTagName
("grade");System.out.println("Grade:
"+ nodeList.item(0).getChildNodes().item(0)
.getNodeValue());nodeList = e.getElementsByTagName
("age");System.out.println("Age:
"+ nodeList.item(0).getChildNodes().item(0)
.getNodeValue());}
}} else
{System.exit(1);}
}} catch (Exception e)
{System.out.println(e);}}
public static void main(String[] args) {XMLParser parser = new XMLParser
();parser.getAllUserNames("c:\\test.xml");}}17.
Convert Array to Map in Javaimport java.util.Map; import
org.apachemons.lang.ArrayUtils; public class Main
{ public static void main(String[] args)
{ String[][] countries = { { "United States",
"New York" }, { "United Kingdom", "London" }, {
"Netherland", "Amsterdam" }, { "Japan", "Tokyo" }, { "France", "Paris" } }; Map countryCapitals =
ArrayUtils.toMap(countries); System.out.println("Capital of Japan is " + countryCapitals.get
("Japan")); System.out.println("Capital of
France is " + countryCapitals.get("France")); }
} import java.util.Map;import org.apachemons.lang.ArrayUtils;public class Main {public static void main(String[] args) {String[][]
countries = { { "United States", "New York" }, { "United Kingdom", "London" },{ "Netherland",
"Amsterdam" }, { "Japan", "Tokyo" }, { "France", "Paris" } };Map countryCapitals = ArrayUtils.toMap(countries);System.out.println("Capital of Japan is " +
countryCapitals.get("Japan"));System.out.println("Capital of
France is " + countryCapitals.get("France"));}}18. Send Email
using Javaimport javax.mail.*; import
javax.mail.internet.*; import java.util.*; public void postMail( String recipients[ ], String subject, String message ,
String from) throws MessagingException {
boolean debug = false; //Set the host smtp address
Properties props = new Properties();
props.put("mail.smtp.host",
"smtp.example"); // create some
properties and get the default Session Session
session = Session.getDefaultInstance(props, null);
session.setDebug(debug); // create a message Message msg = new MimeMessage(session); // set the from and to address
InternetAddress addressFrom = new InternetAddress
(from); msg.setFrom(addressFrom);
InternetAddress[] addressTo = new
InternetAddress[recipients.length]; for (int i =
0; i  recipients.length; i++) {
addressTo = new InternetAddress
(recipients); }
msg.setRecipients(Message.RecipientType.TO,
addressTo); // Optional : You can
also set your custom headers in the Email if you Want
msg.addHeader("MyHeaderName", "myHeaderValue");
// Setting the Subject and Content
Type msg.setSubject(subject);
msg.setContent(message, "text/plain");
Transport.send(msg); } import javax.mail.*;import javax.mail.internet.*;import
java.util.*;public void postMail( String recipients[ ], String subject, String message ,
String from) throws MessagingException{boolean debug =
false;//Set the host smtp addressProperties props = new Properties();props.put
("mail.smtp.host", "smtp.example");// create some properties and get the default
SessionSession session = Session.getDefaultInstance(props,
null);session.setDebug(debug);// create a messageMessage msg = new
MimeMessage(session);// set the from and to addressInternetAddress addressFrom = new InternetAddress(from);msg.setFrom(addressFrom);InternetAddress[] addressTo = new InternetAddress
[recipients.length];for (int i = 0; i  
recipients.length; i++){addressTo = new InternetAddress
(recipients);}msg.setRecipients
(Message.RecipientType.TO, addressTo);// Optional : You can also set your custom headers in the
Email if you Wantmsg.addHeader("MyHeaderName",
"myHeaderValue");// Setting the Subject and Content Typemsg.setSubject(subject);msg.setContent(message,
"text/plain");Transport.send(msg);}19. Send HTTP
request  fetching data using Javaimport java.io.BufferedReader; import
java.io.InputStreamReader; import java.URL;
public class Main { public static
void main(String[] args) {
try {
URL my_url =
new URL("xasxt/mysql/mysql5.1/");nbs
p; BufferedReader br = new BufferedReader(new InputStreamReader(my_url.openStream()));
String
strTemp = "";
while(null
!= (strTemp = br.readLine())){
System.out.println(strTemp);
}
} catch (Exception ex) {
ex.printStackTrace(); }
} } import java.io.BufferedReader;import
java.io.InputStreamReader;import java.URL;public class Main {public static void main(String[] args)
{try {URL my_url = new URL(xasxt/mysql/mysql5.1/); BufferedReader br = new BufferedReader(new InputStreamReader(my_url.openStream()));String strTemp =
"";while(null != (strTemp = br.readLine()))
{System.out.println(strTemp);}
} catch (Exception ex) {ex.printStackTrace
();}}}20. Resize an Array in Java/** * Reallocates an array with a new size, and copies the
contents * of the old array to the new array. * @param
oldArray the old array, to be reallocated. * @param
newSize the new array size. *
@return A new array with the
same contents. */ private static Object resizeArray (Object
oldArray, int newSize) { int oldSize =
java.lang.reflect.Array.getLength(oldArray); Class
elementType = oldArray.getClass().getComponentType(); Object newArray = java.lang.reflect.Array.newInstance(
elementType,newSize); int preserveLength = Math.min
(oldSize,newSize); if (preserveLength  0)
System.arraycopy
(oldArray,0,newArray,0,preserveLength); return
newArray; } // Test routine for
resizeArray(). public static void main (String[] args)
{ int[] a = {1,2,3}; a =
(int[])resizeArray(a,5); a[3] = 4;
a[4] = 5; for (int i=0; i System.out.println (a);
}文章由斐格整理，收集辛苦，希望能保留出处，谢谢斑竹大哥。