http断点续传简单实现（java)

/* '*?WU_L(g  
**SiteFileFetch.java DBCK2PlJ  
*/ Sp^9&^  
package NetFox; "V$Bnz\n  
import java.io.*; `g6h9GC
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import java.net.*; uvV;Mlo]  
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public class SiteFileFetch extends Thread { bIEhgiH  
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SiteInfoBean siteInfoBean = null; //文件信息Bean sRrzp=D  
long[] nStartPos; //开始位置 QNxl/y\l0  
long[] nEndPos; //结束位置 _<NMyRJo  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 a)#1{JaoY  
long nFileLength; //文件长度 *H.oP  
boolean bFirst = true; //是否第一次取文件 RhvfC5Hq  
boolean bStop = false; //停止标志 "B8"_D&  
File tmpFile; //文件下载的临时信息 Ns[ym>x#2  
DataOutputStream output; //输出到文件的输出流 2w-51tqm  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） h<SQL97N  
public SiteFileFetch(SiteInfoBean bean) throws IOException Ko/ I#)  
{ y;AL'vm9  
siteInfoBean = bean; K%X^n>O7C  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); &ZX{R#[L  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 8kIR y  
if(tmpFile.exists ()) =n' 4?W@  
{ ^-[?#]  
bFirst = false; gW1b~( fD  
read_nPos(); %0mMz.
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} [_.5RPJP8  
else mUz\ra;z  
{ 6^c>,.R  
nStartPos = new long[bean.getNSplitter()]; ^+m+zd_  
nEndPos = new long[bean.getNSplitter()]; i6 (a@KRY  
} ZU9c 5/J  
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} (<Th=Fns?  
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public void run() N]<!j$pOz  
{ L   
//获得文件长度 ~2zMkVH  
//分割文件 0sh/|`\  
//实例FileSplitterFetch zWb4([P;  
//启动FileSplitterFetch线程 Xj5~%DZp  
//等待子线程返回 XFh>U7z.  
try{ DmBS0NyR7Y  
if(bFirst) B-T/V-c7  
{ _"#!e{N|  
nFileLength = getFileSize(); n]u<!.X  
if(nFileLength == -1) yH<$k^0r*  
{ EgDQ+( -  
System.err.println("File Length is not known!"); H=\!2XS  
} )5.C]4jol  
else if(nFileLength == -2) ZZ.m(ATR  
{ D^-7JbE]  
System.err.println("File is not access!"); Kmdlf,[3d  
} RJON90,J  
else cn- nj]  
{ ( &frUQm  
for(int i=0;i<nStartPos.length;i++)  =Mb1o[  
{ (}
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nStartPos = (long)(i*(nFileLength/nStartPos.length)); h#hxOVl%x  
}
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for(int i=0;i<nEndPos.length-1;i++) I6s3+x;O  
{ |/|  
nEndPos = nStartPos[i+1]; `WOYoec   
} yj$TPe_BW  
nEndPos[nEndPos.length-1] = nFileLength; ZDC9oX @  
} bI y sl  
} >R2SQA o  
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//启动子线程
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fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; !!:LJ  
for(int i=0;i<nStartPos.length;i++) d.2mT?`#  
{ v
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fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), PccB]  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), .?>5-od2  
nStartPos,nEndPos,i); snt(IJQ  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 7 uarh!  
fileSplitterFetch.start(); n 8pt\i0  
} _6Eu2|vM&  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 7'-j%!#w  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); "sgjWo6  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", P/ oXDI8  
nEndPos = " + nFileLength); tWdhDt8$&  
// fileSplitterFetch[nPos.length-1].start(); Fbp{,V@F2  
07/L}b`P  
Y=T'WNaL)0  
//等待子线程结束 ZK'-U,Y.H7  
//int count = 0; 0iZGPe~  
//是否结束while循环 ~kCwJ<E  
boolean breakWhile = false; & ``d  
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while(!bStop) oiH|uIsqR  
{ #D
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write_nPos(); /S\cU`ZVe  
Utility.sleep(500); fN "tA  
breakWhile = true; =U. b% uC  
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for(int i=0;i<nStartPos.length;i++) gLSA!#[h  
{
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if(!fileSplitterFetch.bDownOver) =]>NDWqpHN  
{ f2,1<^{  
breakWhile = false; P=5NKg  
break; <q,+ON\'  
} Cj*-[EL<  
} dtAbc7
 
if(breakWhile)  pAu72O?  
break; M- 0i7%  
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//count++; K{l5m{:%  
//if(count>4) S }>n1F_
 
// siteStop(); cMzkL%  
} M/*NM= -a  
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System.err.println("文件下载结束！"); UHGcnz<  
} .!}hhiF,Z  
catch(Exception e){e.printStackTrace ();} /i)Hb`(S  
} IOK}+C0e  
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//获得文件长度 SLhEc  
public long getFileSize() !Do,>gO  
{ B/"2.,  
int nFileLength = -1; MbXq`%  
try{ lr2rQo>  
URL url = new URL(siteInfoBean.getSSiteURL()); fRm}S>Nibb  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); p[WX'M0f  
httpConnection.setRequestProperty("User-Agent","NetFox"); y>\S@I  
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int responseCode=httpConnection.getResponseCode(); {5%/T,  
if(responseCode>=400) +^6}   
{ n$2RCQ  
processErrorCode(responseCode); C
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return -2; //-2 represent access is error jLcHY-P0V  
} %TrF0{NR90  
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String sHeader; =ex'22  
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for(int i=1;;i++) &!35/:~uD  
{ Ih1|LR/c  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); *T4<&  
//Utility.log(in.readLine()); XtBMp=7Oa  
sHeader=httpConnection.getHeaderFieldKey(i); y7<&vIEC  
if(sHeader!=null) Napf"Av  
{ \%,&~4 !  
if(sHeader.equals("Content-Length")) Y~n`~(  
{ fn9#>~vrD  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); s%;<O:x8o  
break; "D*
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} &B!%fd.'  
} F3Zxhk
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else J -Qh/d%]  
break; i9UI,b%X  
} uv4 _:   
} Wn!G.(Jq  
catch(IOException e){e.printStackTrace ();} 3z{S}~  
catch(Exception e){e.printStackTrace ();} 4x'AC%&Qi  
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Utility.log(nFileLength); jiIST^Zq#t  
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return nFileLength; ke/_k/  
} W'_/6_c$!  
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//保存下载信息（文件指针位置） f|xLKcOP  
private void write_nPos() C]`eH*z~8  
{ /hdf{4  
try{ v5T9Y-{`  
output = new DataOutputStream(new FileOutputStream(tmpFile)); J-J3=JG  
output.writeInt(nStartPos.length); b2h":G|s  
for(int i=0;i<nStartPos.length;i++) WfGH|u  
{ lv:U%+A  
// output.writeLong(nPos); Fc0jQ@4=  
output.writeLong(fileSplitterFetch.nStartPos); pH9HK  
output.writeLong(fileSplitterFetch.nEndPos); h'^FrWaU/  
} ZHy><=2  
output.close(); ?gV'(3 !  
} /aUFc'5  
catch(IOException e){e.printStackTrace ();} Z|^MGyn  
catch(Exception e){e.printStackTrace ();} CKTrZxR"  
} %OI4a5V*l  
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//读取保存的下载信息（文件指针位置） xaXV^ZM3  
private void read_nPos() =cfm=+  
{ 0->/`/xm  
try{ $ u2Cd4  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); _1JmjIH)M  
int nCount = input.readInt(); PI7IBI  
nStartPos = new long[nCount]; ) YSh D  
nEndPos = new long[nCount]; 5_G'68;OV  
for(int i=0;i<nStartPos.length;i++) L? ;/cO^  
{ ,0T)Oc|HL/  
nStartPos = input.readLong(); - 8syjKTg  
nEndPos = input.readLong(); xQz
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} "2h5m4  
input.close(); A9BxwQU#  
} b*9e1/]  
catch(IOException e){e.printStackTrace ();} QAvWJydb  
catch(Exception e){e.printStackTrace ();} ;]h.m)~|  
} ,L-C(j  
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private void processErrorCode(int nErrorCode) v7@
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{ Qp&?L"U)2  
System.err.println("Error Code : " + nErrorCode);  nhfwOS  
} F7uhuqA]N  
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//停止文件下载 LrM}?9'  
public void siteStop() Y}/jR6hK  
{ q[boWW  
bStop = true; ZA.fa0n
  
for(int i=0;i<nStartPos.length;i++) ",ad7Y7i  
fileSplitterFetch.splitterStop(); yQS04Bl]  

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} Ck(.N  
} v,\93mNp[  
//负责部分文件的抓取 I2*oTUSik  
**FileSplitterFetch.java |p'i,.(c_W  
*/ (^S5Sc=  
package NetFox; `9EVB;  
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import java.io.*; zMU68vwM  
import java.net.*; pSrsp r  
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public class FileSplitterFetch extends Thread { ocP*\NR  
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String sURL; //File URL Y?.gfEXSQo  
long nStartPos; //File Snippet Start Position >'0lw+a  
long nEndPos; //File Snippet End Position g!`BXmW  
int nThreadID; //Thread's ID ,$i<@2/=m  
boolean bDownOver = false; //Downing is over Qrz*Lvle h  
boolean bStop = false; //Stop identical X0x_+b? _  
FileAccessI fileAccessI = null; //File Access interface ]1Qi=2'  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 9R:(^8P8  
{ 'WnpwY  
this.sURL = sURL; O<iI  
this.nStartPos = nStart; Ey= 4 b  
this.nEndPos = nEnd; 8a!2zwUBV  
nThreadID = id; ULbP_y>(Y  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 #x|VfN5f  
} 7n>|D^  
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public void run() C!kbZTO[p"  
{ #J3zTG(:@  
while(nStartPos < nEndPos && !bStop) Ris-tdg  
{ c.6QhE  
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try{ /]l f>\x1  
URL url = new URL(sURL); s|p(KWo2U  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); +TW
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httpConnection.setRequestProperty("User-Agent","NetFox"); +ks$UvtY  
String sProperty = "bytes="+nStartPos+"-"; xx}'l:}2]  
httpConnection.setRequestProperty("RANGE",sProperty); L.Vq1RU\"  
Utility.log(sProperty); 6fQ*X~| p  
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InputStream input = httpConnection.getInputStream(); rX)o3>q^?  
//logResponseHead(httpConnection); %SFw~%@3&~  
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byte[] b = new byte[1024]; tdb4?^.s  
int nRead; fIlIH  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) u4xA'X'~R  
{ Z_!9iA:X  
nStartPos += fileAccessI.write(b,0,nRead); ^zkd{ov  
//if(nThreadID == 1) `O jvt-5}E  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); J b|mXNcL  
} X[Y#+z4  
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Utility.log("Thread " + nThreadID + " is over!"); ~JT lPU'  
bDownOver = true; >d)|r  
//nPos = fileAccessI.write (b,0,nRead); _qk9o  
} rcpvH}N:  
catch(Exception e){e.printStackTrace ();} hXBqz9
 
} Zm5nLxM  
} ]#+5)[N$>  
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//打印回应的头信息 J~:kuf21  
public void logResponseHead(HttpURLConnection con) 2%*|fF}I  
{ Dj/Q1KY$m  
for(int i=1;;i++) -1#e^9Ve\  
{ Vc{/o=1u  
String header=con.getHeaderFieldKey(i); Wa@6VY  
if(header!=null) $t%"Tr  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); *E$H;wKs8  
Utility.log(header+" : "+con.getHeaderField(header)); @$_rEdwi  
else l'P[5'.  
break; Y~<rQ  
} b<48#Qy~l  
} ,\Z8*Jr3Q  
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public void splitterStop() mn,=V[f  
{ #`2GAM];7  
bStop = true; 7Ljs4>%l9j  
} chMt5L+5  
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} D_]i/ F%  
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/* I*%&)Hj~  
**FileAccess.java g
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*//文件访问(定位，写) t^dakL  
package NetFox; !<JG&9ODP  
import java.io.*; HP1X\h!Ke  
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public class FileAccessI implements Serializable{ tauP1&%oH{  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 {5?!`<fF  
RandomAccessFile oSavedFile; IiQWs1  
long nPos;  W\zL  
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public FileAccessI() throws IOException Q
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{ m mw)C"  
this("",0); t(Cq(.u`:  
} \v B9fA:*  
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public FileAccessI(String sName,long nPos) throws IOException 3RG/X  
{ jnx+wcd  
oSavedFile = new RandomAccessFile(sName,"rw"); ;L MEU_  
this.nPos = nPos; "dFdOb"O-  
oSavedFile.seek(nPos); .T[!!z#^  
} u&Ie%@:h9R  
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public synchronized int write(byte[] b,int nStart,int nLen) C]{V%jU  
{ E$oA+n~  
int n = -1; `3H?*\<(
 
try{ *&~sr  
oSavedFile.write(b,nStart,nLen); Bil;@,Z#  
n = nLen; M]pel\{M  
} X,Q6  
catch(IOException e) |ijW_r  
{ _
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e.printStackTrace (); _j|n}7a  
} GNj/jU<o!  
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return n; cftn`:(&8  
} FeincZ!M  
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} mw%[qeLV  
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/* V9);kD  
**SiteInfoBean.java "J0Oa?  
*/ B_6v'=7]  
package NetFox; 6='_+{   
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public class SiteInfoBean { Z"PDOwj5  
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private String sSiteURL; //Site's URL D[FfJcV'$  
private String sFilePath; //Saved File's Path 9#
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private String sFileName; //Saved File's Name eo}S01bt  
private int nSplitter; //Count of Splited Downloading File ^me}k{x  
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public SiteInfoBean() UO7a}Tz<  
{//nSplitter的缺省值为5 Iu)(H
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//default value of nSplitter is 5 =QO1FO  
this("","","",5); 2*UE&Gp  
} fQ?n(
 
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) :pV("tHE  
{ PK|`}z9  
sSiteURL= sURL; Z-;uzx  
sFilePath = sPath; n?ZH2dI\0  
sFileName = sName; :[ZC-hc\  
this.nSplitter = nSpiltter; bC,M&<N  
>?uH#%C5  
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} K:Xrfn{s  
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public String getSSiteURL() IQ27FV|3  
{ O(sFs1  
return sSiteURL; 1x<rh\oo  
} =.=. \K  
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public void setSSiteURL(String value) <LA`PbQa  
{ h-v&I>  
sSiteURL = value; |jCE9Ve#  
} 2w.9Q (Sn  
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public String getSFilePath() 0m| Gp  
{ xuH<=-O>ki  
return sFilePath; gQcr'[[a  
} Qak@~b  
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public void setSFilePath(String value) <)*g7  
{ Q`wA"mw6k  
sFilePath = value; C?c-V,  
} p?gLW/n  
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public String getSFileName() HjY-b*B  
{ 7g<`wLAH  
return sFileName; {XUfxNDf  
} xo"4mbTV  

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public void setSFileName(String value) K]]rOF  
{ nO7o7bc  
sFileName = value; (P!reYyM  
} #$z-]i  

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public int getNSplitter() &CP@] pi9L  
{ .g`*cDW^=  
return nSplitter; :phD?\!w8t  
} %a6]gsiv2<  
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public void setNSplitter(int nCount) QNI|h;D  
{ hO@v\@;r  
nSplitter = nCount; wyhf:!-I  
} y Q @=\'  
} EqDYQ 7  
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/* *UxB`iA  
**Utility.java bOGDz|H``  
*/ Ch!Q?4  
package NetFox; g~["O!K3  
ifCGNvDR  
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public class Utility { XI(
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public Utility() *A9{H>Vq  
{ +Y^F>/4=Y  
^
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} k{w^MOHNg  
)Is*- W  
//线程睡眠 64j 4P 7  
public static void sleep(int nSecond) ovoI~k'  
{ eii7pbc  
try{ m%(JRh  
Thread.sleep(nSecond); PC7.+;1  
} )Ua2x@j'C@  
catch(Exception e) z4+6k-#):  
{ p00Bgo  
e.printStackTrace (); v@
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} ;{7lc9uRj  
} @"7dk.|  
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//日志 ~u&O  
public static void log(String sMsg) m95$V&  
{ Q&'Nr3H#tZ  
System.err.println(sMsg); qtwmTT)  
} _~q^YZ  
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public static void log(int sMsg) nt`l6b  
{ RSeezP6#  
System.err.println(sMsg); H 6<@  
} uvM88#  
} `B0*/ml  
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/* 07Cuoqt2  
**TestMethod.java zate%y  
*/ zO]dQ$r\Z  
package NetFox; Q&a<
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d~$t{46  
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public class TestMethod { OHvzK8  
df rr.i  
*4VP5]!  
public TestMethod() sjkl? _  
{ ///xx/weblogic60b2_win.exe g*AqFY7|  
try{ :6iq{XV^  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); !K)|e4$  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); sb5kexGxkc  
SiteFileFetch fileFetch = new SiteFileFetch(bean); PS]XLz  
fileFetch.start(); X0=-{<W  
} <Y
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catch(Exception e){e.printStackTrace ();} \Rt  
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nu-wQr  
} NVPYv#uK  
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public static void main(String[] args) =S +:qk  
{ .}>[Kr  
new TestMethod(); >Cc$ P  
} z<=t3dj  
} #Og_q$})f  
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