http断点续传简单实现（java)

/* nX~sVG{Q  
**SiteFileFetch.java
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*/ '<O& :  
package NetFox; N?aU<-T
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import java.io.*; K.k=\N  
import java.net.*; +g*Ko@]m>  
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public class SiteFileFetch extends Thread { -LF^u;s8&S  
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SiteInfoBean siteInfoBean = null; //文件信息Bean F"_SCA?9?  
long[] nStartPos; //开始位置 -YYQnN  
long[] nEndPos; //结束位置 z5?xmffB  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 U_+>4zdm  
long nFileLength; //文件长度 XWk^$"  
boolean bFirst = true; //是否第一次取文件 Xln'~5~)  
boolean bStop = false; //停止标志 \ /o`CV{O  
File tmpFile; //文件下载的临时信息 ie5"  
DataOutputStream output; //输出到文件的输出流 (%".=x-  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类）
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public SiteFileFetch(SiteInfoBean bean) throws IOException h_J'd
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{ ,oR}0(^"\<  
siteInfoBean = bean; ,>)/y
  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); m}k rG  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); Rh%x5RFFc  
if(tmpFile.exists ()) P*_Q8I)Y  
{ y'{0|Xj  
bFirst = false; 6j0!$q^  
read_nPos(); ;s{rJG{inG  
} P66>w})@  
else (sZB-  
{ yPW?%7 h  
nStartPos = new long[bean.getNSplitter()]; I~Ziq10  
nEndPos = new long[bean.getNSplitter()]; mN,Od?q[  
} V^"5cW  
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} vU::dr  
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public void run() ?me0J3u_  
{ Bc$t`PI  
//获得文件长度 (c_E*>c)  
//分割文件 , j7&(V~  
//实例FileSplitterFetch qXgg"k%A\  
//启动FileSplitterFetch线程 \G2&   
//等待子线程返回 PKk_9Xd  
try{ WEZ)7H  
if(bFirst) M1^pf<!s  
{ A^xDAxk  
nFileLength = getFileSize(); +n7bbuxj(X  
if(nFileLength == -1) M,zUg_@  
{ d(<[$3.  
System.err.println("File Length is not known!"); .z+[3Oj_E  
} #Fq6-]y1")  
else if(nFileLength == -2) {eL XVNR7R  
{ ;V@o 2a  
System.err.println("File is not access!"); G7b>r  
} &G:#7HX@-  
else ;>bcI).  
{ EHmw(%a|+  
for(int i=0;i<nStartPos.length;i++) i.Yz)Bw  
{ +TL5yuA  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); (U4]d`  
} ~m'PAC"Q$  
for(int i=0;i<nEndPos.length-1;i++) dL!PpLR$2  
{ >yiK&LW^?  
nEndPos = nStartPos[i+1];
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} `*^ f =y  
nEndPos[nEndPos.length-1] = nFileLength; fnl~0   
} %8s$l'Q;  
} Xi$2MyRd  
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//启动子线程 cyL"?vR*<  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; R^4JM,v9x`  
for(int i=0;i<nStartPos.length;i++) }Ndknut,  
{ #!qa#.Yi  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Xgou7x<  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 3w6}%=)$8  
nStartPos,nEndPos,i); F$X"?fj  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ?U$H`[VF}  
fileSplitterFetch.start(); 4-1=1)c*  
} +G)L8{FY(  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), hX;JMQ915  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); e'Njl?>3  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 5o-WA1  
nEndPos = " + nFileLength); `saDeur#X  
// fileSplitterFetch[nPos.length-1].start(); D<%/:
M  
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//等待子线程结束 hj[&.w  
//int count = 0; u 6A!Sw  
//是否结束while循环 Xy0*1$IS]  
boolean breakWhile = false; SHWD@WLE4  
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while(!bStop) O!xul$9  
{ N;gI %6  
write_nPos(); ?> )(;Ir9  
Utility.sleep(500); u)J&3Ah%  
breakWhile = true; Mwm9{1{  

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for(int i=0;i<nStartPos.length;i++) 6_}& WjU'  
{ 4Cm+xAXG  
if(!fileSplitterFetch.bDownOver) Vh=10Et  
{ U~H]w,^  
breakWhile = false; .d/e?H:  
break; ,%Sf,h?"^  
} Qx<86aKkF  
} w`ebZa/j  
if(breakWhile) ?y"=jn  
break; .Aj4?AXWc  
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//count++; `?P)RS30  
//if(count>4) pQ2'0u5w5  
// siteStop(); nz
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} nymro[@O~  
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System.err.println("文件下载结束！"); ol#| .a2O  
} tg5G`P5PJ  
catch(Exception e){e.printStackTrace ();} Ct@OS227x  
} % XvJJ  
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//获得文件长度 so=Ux2  
public long getFileSize() KcPI,.4{  
{ Cg#@JuwHa  
int nFileLength = -1; 4 s&9A/&pC  
try{ s[2>r#M  
URL url = new URL(siteInfoBean.getSSiteURL()); JA!?vs  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); S~GL_#a  
httpConnection.setRequestProperty("User-Agent","NetFox"); <e)u8+(  
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int responseCode=httpConnection.getResponseCode(); LeEv']  
if(responseCode>=400) ;Gnk8lIsb  
{ J)I|Xot  
processErrorCode(responseCode); (?y
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return -2; //-2 represent access is error lE|Hp  
} 3]MSS\uB  
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String sHeader; =pa F6!AB  
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for(int i=1;;i++) Ng,<4;  
{ qL;u59  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); S:F8`Gh  
//Utility.log(in.readLine()); 4arqlzlo  
sHeader=httpConnection.getHeaderFieldKey(i); {)K
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if(sHeader!=null) "Qci+Qq  
{ FV~ENpncP  
if(sHeader.equals("Content-Length")) x%]5Q/|Ur  
{ vHmsS\\~9  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); BK*Bw,KQ<  
break; .G/>X%
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} VV'*3/I  
} vr2cDk{  
else og$%`o:{  
break; jXH?os%  
} 1^v?Ly8  
} CO5>Q o  
catch(IOException e){e.printStackTrace ();} K+P:g%M  
catch(Exception e){e.printStackTrace ();} a]]>(Txc  
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Utility.log(nFileLength); e09('SON(  
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return nFileLength; [Z-S0  
} a@?2T,$  
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//保存下载信息（文件指针位置） nm}wdel"  
private void write_nPos() @hVF}ybp  
{ n,l{1 q  
try{ g#}a?kTM@  
output = new DataOutputStream(new FileOutputStream(tmpFile)); T*3>LY+bb  
output.writeInt(nStartPos.length); z Go*N,'  
for(int i=0;i<nStartPos.length;i++) =}pPr]Cc  
{ N"k IQe*}1  
// output.writeLong(nPos); ~tM+!  
output.writeLong(fileSplitterFetch.nStartPos); UB8TrYra  
output.writeLong(fileSplitterFetch.nEndPos); hW Va4  
} ;}W-9=81  
output.close(); a9%^Jvm"  
} HAca'!p  
catch(IOException e){e.printStackTrace ();} &Cykw$s  
catch(Exception e){e.printStackTrace ();} _$vAitUe4S  
} 0x1#^dII  
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//读取保存的下载信息（文件指针位置） Ex`!C]sQ  
private void read_nPos() ]>_Ie?L)<  
{ v<u`wnt  
try{ |,)=-21&;  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); lO+6|oF0  
int nCount = input.readInt(); \2U FJ  
nStartPos = new long[nCount]; _*1{fvv0{  
nEndPos = new long[nCount]; >0c4C<_  
for(int i=0;i<nStartPos.length;i++) @b]?Gg  
{ N*$L#L$*  
nStartPos = input.readLong(); V/,@hv`+  
nEndPos = input.readLong(); Kh'7N!  
} BXj]]S2  
input.close(); {37v.4d;  
} 9]]isE8r  
catch(IOException e){e.printStackTrace ();} CtO;_;eD'  
catch(Exception e){e.printStackTrace ();} 0; PV gO;9  
} h
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private void processErrorCode(int nErrorCode) -:]-g:;/  
{ =ICakh!TO  
System.err.println("Error Code : " + nErrorCode); A@81wv  
} 8p0ZIrD%  
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//停止文件下载 K.P1|  
public void siteStop() @4FG& >kQ  
{ Ro:DAxi@L  
bStop = true; #=V[vbTY  
for(int i=0;i<nStartPos.length;i++) $!q(-+(  
fileSplitterFetch.splitterStop(); W+5<=jXFB  
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} Z!eW_""wp  
} tQYkH$e`/{  
//负责部分文件的抓取 }^a" >$DU  
**FileSplitterFetch.java HA#9y;\  
*/ >JUOS2  
package NetFox; yZc_PC`  
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import java.io.*; z-g"`w:Lj  
import java.net.*; (;6vT'hE  
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public class FileSplitterFetch extends Thread { gAxf5A_x)  
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String sURL; //File URL [,?5}
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long nStartPos; //File Snippet Start Position *^=zQ~  
long nEndPos; //File Snippet End Position E,wOWs*  
int nThreadID; //Thread's ID ,2MLYW,  
boolean bDownOver = false; //Downing is over i[V\RKH*F  
boolean bStop = false; //Stop identical hwj:$mR  
FileAccessI fileAccessI = null; //File Access interface [PP&}.k4"  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException -qNun3  
{ !Sj
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this.sURL = sURL; W9M~2< L  
this.nStartPos = nStart; %}/|/=  
this.nEndPos = nEnd; "x~su?KiA  
nThreadID = id;
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fileAccessI = new FileAccessI(sName,nStartPos);//定位 ]mZN18#  
} \&#IK9x{  
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public void run() Nay&cOz  
{ 3-6Lbe9H  
while(nStartPos < nEndPos && !bStop) XFmTr@\M  
{ !U[/P6 +0  
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try{ 7Bs:u  
URL url = new URL(sURL); (Ee5Af,4  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); nA4PY]  
httpConnection.setRequestProperty("User-Agent","NetFox"); Tk~Y  
String sProperty = "bytes="+nStartPos+"-"; \iQ{Q&JR:  
httpConnection.setRequestProperty("RANGE",sProperty); AdGDs+at,  
Utility.log(sProperty); e,8[fp-7  
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InputStream input = httpConnection.getInputStream(); Zog&:]P'F  
//logResponseHead(httpConnection); !E.CpfaC  
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byte[] b = new byte[1024]; H9+[T3b  
int nRead; &|Cd1z#?  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) $ts1XIK%  
{ ,(y6XUV~  
nStartPos += fileAccessI.write(b,0,nRead); HY>zgf,0  
//if(nThreadID == 1) ?Jy/]j5fI  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 5e|yW0o  
} W\1V`\gF  
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Utility.log("Thread " + nThreadID + " is over!"); D4
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bDownOver = true; oUNuM%g9Dy  
//nPos = fileAccessI.write (b,0,nRead); Dhze2q)o  
} Ra)AQ n  
catch(Exception e){e.printStackTrace ();} _/[}PQC6G  
} ,qu7XFYrY  
} ^_5t5>  
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//打印回应的头信息 F!qt=)V@w  
public void logResponseHead(HttpURLConnection con) o8c5~fG1  
{ <Gw>}/-^  
for(int i=1;;i++) reI4!,x  
{ .9VhDrCK  
String header=con.getHeaderFieldKey(i); k^Qd%;bdF  
if(header!=null) Z3q
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//responseHeaders.put(header,httpConnection.getHeaderField(header)); Boj#r ,x  
Utility.log(header+" : "+con.getHeaderField(header)); >hv8zHOO:  
else ?)V|L~/  
break; kK%@cIXS3  
} CAbR+y  
} K*9~g('  
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public void splitterStop() hn[
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{ opfg %*  
bStop = true; kps}i~Jb  
} |YcYWok  
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} vf0 fa46  
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/* Wf{&D>  
**FileAccess.java awU&{<,=g  
*//文件访问(定位，写) vB Vg/  
package NetFox; n=A}X4^  
import java.io.*; ["0DXm%t  
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public class FileAccessI implements Serializable{ ,Fzuo:{uy  
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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 .kc{)d*0K  
RandomAccessFile oSavedFile; 5
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long nPos; z`:tl7  
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public FileAccessI() throws IOException Fp~0 ^  
{ /
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this("",0); V\*J"ZP&  
} PX>>h}%  
~9Cw5rwH<;  
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public FileAccessI(String sName,long nPos) throws IOException >=K~*$&>  
{ (Qd@Q,@(s  
oSavedFile = new RandomAccessFile(sName,"rw"); <RCeY(1  
this.nPos = nPos; AsO)BeUD  
oSavedFile.seek(nPos); 7bL48W<QD  
} [PH56f  
=|V[^#V  
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public synchronized int write(byte[] b,int nStart,int nLen) F5 7Kr5X  
{
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int n = -1; icN#8\E  
try{ }WnoI2  
oSavedFile.write(b,nStart,nLen); 2[I[I*"_d  
n = nLen;
9t+:L(*pK  
} =VGRM#+D  
catch(IOException e) $D;-;5[-/r  
{ paZcTC  
e.printStackTrace (); `P jS  
} LX</xI08W  
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return n; s)}EMDY  
} 5"z~
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} rqEP!S^  
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/* d=/a{lP\  
**SiteInfoBean.java >x
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*/ ;aImz*1%t  
package NetFox; bYwe/sR  
_Kg"l5?B  
no9=K4h`  
public class SiteInfoBean { )TOKHN  
/vAA]
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&Vbcwv@  
private String sSiteURL; //Site's URL q(Zu;ecBN  
private String sFilePath; //Saved File's Path S#l)|c_~  
private String sFileName; //Saved File's Name -~_;9[uV  
private int nSplitter; //Count of Splited Downloading File $: qrh6
6  
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public SiteInfoBean() ^3ysY24Q  
{//nSplitter的缺省值为5 Kgb<uXk  
//default value of nSplitter is 5 e!P]$em|1E  
this("","","",5); \4n9m  
} lFD/hz7lc  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) /OeOL3Y  
{ ^K[[:7Aem  
sSiteURL= sURL; ~"22X`;h[G  
sFilePath = sPath; ' eH Fa  
sFileName = sName; M4K>/-9X+V  
this.nSplitter = nSpiltter; NLZUAt
x(  
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:JCe,1!3@  
} ]lA.?  
6B@{X^6y  
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public String getSSiteURL() g&O!w!T  
{ +A<7:`sO  
return sSiteURL; g&d tOjM  
} 2qPQ3-'  
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M][Zu[\*  
public void setSSiteURL(String value) GL3olKnL  
{ J4jL%5t  
sSiteURL = value; s`o_ER  
} =:Lc-y>  
6Lz:J:Q)  
B^BbA-I  
public String getSFilePath() AUPTtc`#Y  
{ Bu#\W  
return sFilePath; Mf`@X[-;  
} !\|L(Paf  
;\gHFG}  
y-vQ4G5F|  
public void setSFilePath(String value) }bYk#6KX  
{ 5Cl;h^R|m  
sFilePath = value; c'Zs2s7$  
} wsAijHjJI!  
9P#<T7
  
$GX9-^og=T  
public String getSFileName() B2)SNhF2Y  
{ 2IFEl-IB[  
return sFileName; =
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} %$zX a%A  
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public void setSFileName(String value) ' O d_:]  
{ we2D!Ywr  
sFileName = value; F
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} HsAKz]Mq  
E(0[/N~  
j/w*2+&v  
public int getNSplitter() lU%L  
{ ]L9$JTGF`w  
return nSplitter; {KM5pK?,BJ  
} 'L ]k\GO  

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public void setNSplitter(int nCount) mW_ N-z  
{ +{@hD+  
nSplitter = nCount;
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} S01
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} 'v_VyK*w  
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fz`\-"f]  
/* LABLT;c  
**Utility.java yn KgNi  
*/ 9vJ'9Z2\  
package NetFox; .?;"iv+  
U$AV"F&!&}  
"78BApjWT6  
public class Utility { rWxQ;bb#  
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public Utility() o :_'R5  
{ d/&~IR  
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y<*/\]t9L[  
} V"Y-|R  
+4m~D`fqt[  
//线程睡眠 uz[5h0c  
public static void sleep(int nSecond) mNnt9F3Eq  
{ d9yfSZ  
try{ f>jAu;S  
Thread.sleep(nSecond); 7Un5Y[FZo  
} _J-3{a  
catch(Exception e) `T~~yM)q  
{ rd!4u14  
e.printStackTrace (); g;t>jgX  
} Yp8GW1@  
} V]0~BV  
~6O<5@k  
//日志 e$=0.GWT  
public static void log(String sMsg) -KFozwr5/  
{ m{C  
System.err.println(sMsg); FvV:$V|  
} H?W8_XiN  
2JS&
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<R@w
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public static void log(int sMsg) j5]6CG_  
{ 9M!J7 W  
System.err.println(sMsg); $ru()/pI)z  
} pv){R;f  
} t&L+]I'P3  
p:CpY'KV_  
)TV{n#n  
/* NY9\a[[^[8  
**TestMethod.java xcA5  
*/ QeZK&^W  
package NetFox; j1
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pv9Z-WCix$  
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public class TestMethod { AQa;D2B$  
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public TestMethod() ^-GzWT  
{ ///xx/weblogic60b2_win.exe L! DK2,  
try{ zs@xw@  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 
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//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); cas5  
SiteFileFetch fileFetch = new SiteFileFetch(bean); :Lze8oY(D}  
fileFetch.start(); c-gpO|4>  
} 6o!Y^^/U  
catch(Exception e){e.printStackTrace ();} HbXYinG%  
hxQx$  
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} 9C2DW,?  
`;vJ\$-<  
/>q?H)6  
public static void main(String[] args) W|e$@
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{ >GV= %  
new TestMethod(); krI@N}OU  
} J;AwC>N  
} LWp#i8,  
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