http断点续传简单实现（java)

/* `dw">z,  
**SiteFileFetch.java mqHcD8X  
*/ #SKC>MGz  
package NetFox; ~!S/{Un   
import java.io.*; mPU}]1*p  
import java.net.*; @F]w]d  
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public class SiteFileFetch extends Thread { eR4ib-nS  
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SiteInfoBean siteInfoBean = null; //文件信息Bean -oUGmV_  
long[] nStartPos; //开始位置 #|K{txC   
long[] nEndPos; //结束位置 tm/=Oc1p  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 X::@2{-@y  
long nFileLength; //文件长度 \=D+7'3  
boolean bFirst = true; //是否第一次取文件 +oh|r'~  
boolean bStop = false; //停止标志 Nyt*mbd5 {  
File tmpFile; //文件下载的临时信息 k-H6c  
DataOutputStream output; //输出到文件的输出流 Zb=;\l*&  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） _CPj]m{  
public SiteFileFetch(SiteInfoBean bean) throws IOException cRH(@b Xr  
{ wo+`WnDh  
siteInfoBean = bean; sj4\lpZ3h  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); L pq)TE#  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); X{Fr  
if(tmpFile.exists ()) o{>4PZ}=g  
{ X1d{7H8A2  
bFirst = false; 1d~d1Rd  
read_nPos(); je@&|9h  
} &c 2Qa  
else J6[}o4Z  
{ r95,X!  
nStartPos = new long[bean.getNSplitter()]; T ay226  
nEndPos = new long[bean.getNSplitter()]; zJP jsD]  
} `+T 2IPN  
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} |fywqQFq  
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public void run() #q K.AZi  
{ J90:c@O"w  
//获得文件长度 cpl Ny?UIC  
//分割文件 Ux1j+}y  
//实例FileSplitterFetch -8l(eDm"m  
//启动FileSplitterFetch线程 sZ~03
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//等待子线程返回 |||m5(`S  
try{ ^mjU3q{;  
if(bFirst) SHs [te[  
{ XlD=<$Nk7  
nFileLength = getFileSize(); !yT=*Cj4  
if(nFileLength == -1) p6NPWaBR  
{ _h4]gZ  
System.err.println("File Length is not known!"); q6N{N
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} akk*f+TD`  
else if(nFileLength == -2) FAL#p$y}  
{  ZB|s/  
System.err.println("File is not access!"); B8eZ}9X  
} qE3Ud:j  
else ]zVQL_%,  
{ C[<{>fl)  
for(int i=0;i<nStartPos.length;i++) 'zav%}b]L  
{ p+<qI~  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); p2Gd6v.t  
} V dvj*I
 
for(int i=0;i<nEndPos.length-1;i++)  ]Tb?z&  
{ k~so+k&=b  
nEndPos = nStartPos[i+1]; ,tQNL\t  
} Y@:l!4DI  
nEndPos[nEndPos.length-1] = nFileLength; _f8H%Kgk;  
} 5=8v\q?)c  
} G
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//启动子线程 JBA{i45x  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; rz,,ku4qt  
for(int i=0;i<nStartPos.length;i++) 8\9W:D@"x  
{ @GD $KR9  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ?*$uj(  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), lz6CK  
nStartPos,nEndPos,i); n|?sNM<J3  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); zRmVV}b  
fileSplitterFetch.start(); H;NAS/OhS  
} wl%ysM|x  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), m' S{P:TK  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); A W6B[  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", g33Y$Xdk  
nEndPos = " + nFileLength); @{{L1[~:0  
// fileSplitterFetch[nPos.length-1].start(); WV'u}-v^  
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//等待子线程结束 6w? GeJ  
//int count = 0; ^V1\boo=  
//是否结束while循环 g]JRAM  
boolean breakWhile = false; Gh.?6kuh  
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while(!bStop) *~4<CP+"0  
{
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write_nPos(); 88<d<)7t  
Utility.sleep(500); yPT o,,ca=  
breakWhile = true; KPDJ$,
:  
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for(int i=0;i<nStartPos.length;i++) (=WbLNBS  
{ S&-F(#CF^  
if(!fileSplitterFetch.bDownOver) ;7EeRM*  
{ w2
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breakWhile = false; L4T\mP7D7*  
break; |A,.mOT  
} '5*&  
} `KLr!<i()  
if(breakWhile) N-b'O`C  
break; fj['M6+wd  
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//count++; %-fS:~$  
//if(count>4) p %.Adxx  
// siteStop(); p<h(  
} bC"h7$3  
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System.err.println("文件下载结束！"); J=8Y D"1  
} z>0$SBQ-  
catch(Exception e){e.printStackTrace ();} cZ !$XXA`  
} }@jJv||  
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//获得文件长度 l&e{GHz  
public long getFileSize() O(-6Zqk8Q  
{ 6:8Nz   
int nFileLength = -1; kG9aHWw  
try{ >EA\KrjW  
URL url = new URL(siteInfoBean.getSSiteURL()); b?cO+PY01  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); G9xO>Xp^Al  
httpConnection.setRequestProperty("User-Agent","NetFox"); I(kEvfxc"  
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int responseCode=httpConnection.getResponseCode(); gBWr)R  
if(responseCode>=400) RrH{Y0  
{ |H,WFw1%}  
processErrorCode(responseCode); R>~I8k
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return -2; //-2 represent access is error \(=xc2  
} 5+Tx01)  
8[t*VIXI  

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String sHeader; nO'C2)bBSG  
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for(int i=1;;i++) DzA'MX  
{ htrtiJ1  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); i"Hc(lg  
//Utility.log(in.readLine()); A7XA?>~+|  
sHeader=httpConnection.getHeaderFieldKey(i);
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if(sHeader!=null) D+ .vg?8  
{ Z  eY*5m  
if(sHeader.equals("Content-Length")) _-#o[>2[  
{ MQcIH2  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); uTz>I'f  
break; ek/zQM@%  
} lb*;Z7fx<'  
} ">h$(WCK  
else thX4-'i  
break; 90Sras>F  
} bQ 0Ab"+D  
} [e_csQ  
catch(IOException e){e.printStackTrace ();} sUR5Q/Q  
catch(Exception e){e.printStackTrace ();} FqGMHM\J  
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Utility.log(nFileLength); nQ|($V1?W  
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return nFileLength; qe?Ns+j<d  
} I`jG  
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//保存下载信息（文件指针位置） l_9ZzN  
private void write_nPos() &Qj1uf92.  
{ 9C Ki$L  
try{ ~@QAa (P.  
output = new DataOutputStream(new FileOutputStream(tmpFile)); m:
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output.writeInt(nStartPos.length); .X)Wb{7  
for(int i=0;i<nStartPos.length;i++) 5A5t
 
{ -#G>`T~  
// output.writeLong(nPos); _\,lv \u  
output.writeLong(fileSplitterFetch.nStartPos); [h&s<<# D  
output.writeLong(fileSplitterFetch.nEndPos); c=?6`m,"M  
} z?VjlA(X  
output.close(); YwZx{%
f  
} 4s'%BM-r-  
catch(IOException e){e.printStackTrace ();} L:?Ew9Lf  
catch(Exception e){e.printStackTrace ();} /[/{m]  
} *}Gys/\!S  
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//读取保存的下载信息（文件指针位置） 1=9GV+`n  
private void read_nPos() }hm_Ws  
{ Z!fbc#L6  
try{ ypemp=+(r  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); -`z%<)!Y  
int nCount = input.readInt(); >o`+j$j  
nStartPos = new long[nCount]; UH+#Nel+!  
nEndPos = new long[nCount]; L})*ck
 
for(int i=0;i<nStartPos.length;i++) x;} 25A|  
{ _(~E8g  
nStartPos = input.readLong(); UmMu|`  
nEndPos = input.readLong(); *V+,X  
} xC0y2+)|  
input.close(); ea`6J  
} ,z`D}<3  
catch(IOException e){e.printStackTrace ();} kSCpr0c  
catch(Exception e){e.printStackTrace ();} &%)F5PT  
} vd$>nJ"  
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private void processErrorCode(int nErrorCode) M0)0~#?.D  
{ 2>9..c  
System.err.println("Error Code : " + nErrorCode); FjiIB1 T  
} SfrM|o  
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//停止文件下载 Y,,Z47% E  
public void siteStop() hcYqiM@8>  
{ BXxJra/V  
bStop = true; xb9^WvV  
for(int i=0;i<nStartPos.length;i++) (Nd)$Oq[4  
fileSplitterFetch.splitterStop(); K)[\IJJM  
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} =`N0  
} Buq(L6P9r  
//负责部分文件的抓取 EKN<KnU%  
**FileSplitterFetch.java ]-a
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*/ ~q/~ u  
package NetFox; kJNg>SN*@#  
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import java.io.*; -{z[.v.p  
import java.net.*; 'IVC!uL,%  
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public class FileSplitterFetch extends Thread { 'dzbeTJD5  
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String sURL; //File URL Eg2jexl
 
long nStartPos; //File Snippet Start Position )S`Yl;oL  
long nEndPos; //File Snippet End Position v"%>ms"n  
int nThreadID; //Thread's ID r9b(d]  
boolean bDownOver = false; //Downing is over Q[H4l({E  
boolean bStop = false; //Stop identical s,/C^E  
FileAccessI fileAccessI = null; //File Access interface O ]-8 %  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException *r9D+}Y(4  
{ At[Sk
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this.sURL = sURL; 9oP  
this.nStartPos = nStart; "qZTgCOY2  
this.nEndPos = nEnd; F
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nThreadID = id; I.~=\%Z{  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 ,qV7$u  
} b`DPlQHj  
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public void run() _ogN  
{ +~,q"
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while(nStartPos < nEndPos && !bStop) \FCPD.2s+  
{ i/!KUbt  
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try{ /Zx"BSu
 
URL url = new URL(sURL); SymlirL  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); _pvt,pW  
httpConnection.setRequestProperty("User-Agent","NetFox"); L/GVQj
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String sProperty = "bytes="+nStartPos+"-"; 8)Vl2z  
httpConnection.setRequestProperty("RANGE",sProperty); qAlX#]  
Utility.log(sProperty); HB.:/5\  
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InputStream input = httpConnection.getInputStream(); Dd, &a  
//logResponseHead(httpConnection); XI`s M~'  
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byte[] b = new byte[1024]; P~x4h{~Gd  
int nRead; Zk|PQfi+  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) )`gxaT>&l  
{ H3iYE~^#  
nStartPos += fileAccessI.write(b,0,nRead); KMl3`+i  
//if(nThreadID == 1) 9>&p:+D  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); t
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} 'b>3:&  
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Utility.log("Thread " + nThreadID + " is over!"); j~9Y0jz_  
bDownOver = true; }y(cv}8
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//nPos = fileAccessI.write (b,0,nRead); c0X1})q$  
} c2s73iz  
catch(Exception e){e.printStackTrace ();} o(D_ /]'8  
} 20Jlf?  
} L$,Kdpj  
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//打印回应的头信息 #0^a-47PA<  
public void logResponseHead(HttpURLConnection con) N?A}WW#  
{ K,P`V &m?  
for(int i=1;;i++) C&EA@U5X^  
{ AnZy oa  
String header=con.getHeaderFieldKey(i); ~~p)_  
if(header!=null) }<'ki ;  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); tv]9n8v  
Utility.log(header+" : "+con.getHeaderField(header)); {8%KO1xB  
else HuN_$aP  
break; oIE3`\xS  
} 9c0
  
} R-4#y%k<  
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public void splitterStop() \,!Qo*vj  
{ IRv/[|"L  
bStop = true; Ca/N'|}^  
} ]4lC/&nm  
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} ybIqn0&[  

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/* Tg=P*HY6  
**FileAccess.java yhnPS4DC  
*//文件访问(定位，写) x69RQ+Vw  
package NetFox; l @E {K|
 
import java.io.*; fP\*5|7%R  
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public class FileAccessI implements Serializable{ :j32 :/u  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 >LVGNicQ  
RandomAccessFile oSavedFile; 3A! |M5  
long nPos; LMp^]*)t  
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public FileAccessI() throws IOException YYe=
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{ -V'Y
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this("",0); |#(y?! A^  
} cCG!X%9  
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public FileAccessI(String sName,long nPos) throws IOException _+Pz~_+kS  
{ 'PTQ S,E  
oSavedFile = new RandomAccessFile(sName,"rw"); 2frwU~y  
this.nPos = nPos; Ju"c!vu~  
oSavedFile.seek(nPos); @ykl:K%ke  
} Nr*o RYY  

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+Je%8jH  
public synchronized int write(byte[] b,int nStart,int nLen) fUq #mkq}  
{ h5v=h>c  
int n = -1; .W\x{h  
try{ PM)nw;nS  
oSavedFile.write(b,nStart,nLen); gBXoEn]
 
n = nLen; {!1Rl
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} e=[@HVr   
catch(IOException e) hN\Q&F!  
{ xo!2GPD.  
e.printStackTrace (); Y7')~C`up^  
} `"#hhKG  
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return n; n3\~H9  
} q{xF7}i  
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} 'sa>G  
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/* X7*fmD=Uy  
**SiteInfoBean.java =9:gW5F69  
*/ Jpn= ^f[rm  
package NetFox; 8RcLs1n/  
J(9{P/  
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public class SiteInfoBean {
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private String sSiteURL; //Site's URL }>b@=5O  
private String sFilePath; //Saved File's Path wVF qkJ  
private String sFileName; //Saved File's Name LMLrH.  
private int nSplitter; //Count of Splited Downloading File 1c*;Lr.K  
u Vo"_c w  

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public SiteInfoBean() l.BiE<&  
{//nSplitter的缺省值为5 c^z)[  
//default value of nSplitter is 5 qu;$I'Ul%  
this("","","",5); C4 -y%W"P  
} `yC[Fn"E^  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) FyNm1QNy^  
{ x-b}S1@  
sSiteURL= sURL; @yF>=5z:  
sFilePath = sPath; blkPsp)m"  
sFileName = sName; m\MI 6/  
this.nSplitter = nSpiltter; 3XDuo|(  
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} u>*q
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^AoX|R[1%  
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public String getSSiteURL() (g1Op~EM  
{ G[{Av5g mx  
return sSiteURL; vTC{  
} 6;(b-D
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i\x@s>@x}  
public void setSSiteURL(String value) xWM?E1@  
{ n"@){:{4?  
sSiteURL = value; h+j*vX/!  
} & u6ydN1xe  
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public String getSFilePath() Uz%ynH  
{ Zu94dF
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return sFilePath; i9T<(sdK+  
} 35:R
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public void setSFilePath(String value) ^UFNds'q  
{
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sFilePath = value; VLoRS)   
} $UpWlYwG  
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public String getSFileName() UUF]45t>  
{ C u
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return sFileName; B;2#Sa.  
} KDj/
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public void setSFileName(String value) ;J:*r0  
{ $f>(T
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sFileName = value; q(Ow:3&  
} *w}r:04F  
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public int getNSplitter() !>/J]/4>  
{  i(V  
return nSplitter; !/X>k{  
} \S{ihS@J  
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public void setNSplitter(int nCount) a%?v/Ku  
{ q d:"LS  
nSplitter = nCount; 4JXJ0T ar  
} z0F55<i  
} nswhYSX  
!_W']Crb]]  
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/* 2-@t,T  
**Utility.java ;Zn&Nc7  
*/ !sYZ1;WAO  
package NetFox; :z6?  
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}9FWtXAU^1  
public class Utility { D[4%CQ1m  
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?~cO\(TY["  
public Utility() ezri9\Ju  
{
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} GH&5m44  
*xpPD\{k  
//线程睡眠 ~RZN+N  
public static void sleep(int nSecond) nP|ah~ q  
{ ngk:q5Tp  
try{ ^ (J%)&_\3  
Thread.sleep(nSecond); Nz%pl!  
} J|HV8  
catch(Exception e) B[2t.d;h  
{ N x
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e.printStackTrace (); E,ooD3$h  
} i+lq:St  
} G;USVF-'K  
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//日志 K1-RJj\L  
public static void log(String sMsg) -iFFXESVX  
{ *z_`$Y
  
System.err.println(sMsg); 17w{hK4o8O  
} u=E &jL5U  
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public static void log(int sMsg) A;f)`i0l,  
{ %CgmZTz~<  
System.err.println(sMsg); <TSps!(#  
} !>&G+R+k  
} J%fJF//U  
a FWTm,)  
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/* >)mF'w  
**TestMethod.java KvI/!hl\  
*/ "cbJ{ G1pk  
package NetFox; ?DnQU"_$  
~
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public class TestMethod { 9<"F3F0|  
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public TestMethod() $jBi~QqOf  
{ ///xx/weblogic60b2_win.exe {xP-p"?p  
try{ =c]We:I  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); i?)bF!J  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); D>`{f4Y  
SiteFileFetch fileFetch = new SiteFileFetch(bean); f<R 3ND)  
fileFetch.start(); b>d]= u  
} kHQn'r6  
catch(Exception e){e.printStackTrace ();} WMFn#.aY5  
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} PAVlZ}kj  
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public static void main(String[] args) 5cl^:Ua  
{ h-o;
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new TestMethod(); e"Z,!Q^-L  
} kpk ^Uw%f  
} v~p?YYOm<  
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