http断点续传简单实现（java)

/* mYxyWB  
**SiteFileFetch.java jN31hDg<z  
*/ G{Yz8]m  
package NetFox; vb Y3;+M>  
import java.io.*; 6e,xDr  
import java.net.*; .IarkeCtb  
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public class SiteFileFetch extends Thread { oF]cTAqhC.  
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SiteInfoBean siteInfoBean = null; //文件信息Bean #KxbM-1=  
long[] nStartPos; //开始位置 e~l#4{w  
long[] nEndPos; //结束位置 ;U9J++\d<A  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 5xCT~y/a  
long nFileLength; //文件长度 8:=n*  
boolean bFirst = true; //是否第一次取文件 +Hvc_Av''  
boolean bStop = false; //停止标志 sRSz}]  
File tmpFile; //文件下载的临时信息 \u,}vppz  
DataOutputStream output; //输出到文件的输出流 =Prb'8 W  
: _e#  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） 1MlUG5  
public SiteFileFetch(SiteInfoBean bean) throws IOException ?BA]7M(,4  
{ 6W[}$#w  
siteInfoBean = bean; IW=cym7  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); {n#k,b&9B  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); E>b2+;Jv  
if(tmpFile.exists ()) 9,uhfb^]  
{ Vj<:GRNQ,d  
bFirst = false; e^p +1-B  
read_nPos(); N|N3x7=gs  
} MP Z3D9  
else v ^[39*8  
{ F{06 _T  
nStartPos = new long[bean.getNSplitter()]; {]_uMg#
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nEndPos = new long[bean.getNSplitter()]; [^CV>RuO  
} [.se|]t7X  
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} PyVC}dUAX  
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public void run() 4iAZ+l5&  
{ 'c2W}$q  
//获得文件长度 =4V&*go*\  
//分割文件 pl@O N"=[  
//实例FileSplitterFetch
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//启动FileSplitterFetch线程 OsBo+fwT  
//等待子线程返回 <,o>Wx*1C  
try{ W} WI; cI  
if(bFirst) Lbe\@S  
{ .2d9?p3Y  
nFileLength = getFileSize(); We0.3aG  
if(nFileLength == -1) r/
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{ Grs]d-xI  
System.err.println("File Length is not known!"); mxor1P#|  
} x{D yTtX<  
else if(nFileLength == -2) QaUm1i#
 
{ +uay(3m((  
System.err.println("File is not access!"); bvfk  
} ^,m< 9  
else P96pm6H_;  
{
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for(int i=0;i<nStartPos.length;i++) zvABU+{jD  
{ R1Sy9x .  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); HhO".GA  
} oFOnjK"|F  
for(int i=0;i<nEndPos.length-1;i++) %ZHP2j %~  
{ "KcA  
nEndPos = nStartPos[i+1]; n>@oBG)!  
} >WY#4  
nEndPos[nEndPos.length-1] = nFileLength; DN4$Jva  
} ga?*DI8w  
} (&/2\0QV  
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%$%&m1Y  
//启动子线程 {U&.D [{&  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; vJAZ%aW  
for(int i=0;i<nStartPos.length;i++) !9 fz(9  
{ :W b j\  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Ol4+_n8xj  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),  >S$Z  
nStartPos,nEndPos,i); ss;R8:5  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 8~5cJPi6  
fileSplitterFetch.start(); a0r"N[&  
} l7&$}x-  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), hiNEJ_f  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); SG6sw]x  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", j*~T1i
 
nEndPos = " + nFileLength); L^Jk=8  
// fileSplitterFetch[nPos.length-1].start(); =zwOq(Bh W  
~]ZpA-*@Ut  
N !TW!  
//等待子线程结束 (O0Urm  
//int count = 0; R|i/lEq  
//是否结束while循环 qI^ /"k*5  
boolean breakWhile = false; n3J53| %v  
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while(!bStop) B"%{i-v>**  
{ AT5aDEb^^  
write_nPos(); c-.t>r&  
Utility.sleep(500); $-[CG7VgX%  
breakWhile = true; 1S@vGq}  
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for(int i=0;i<nStartPos.length;i++) A*W)bZs.  
{ 6e7{Iy  
if(!fileSplitterFetch.bDownOver) )7_"wD` z  
{ Z@hD(MS(C  
breakWhile = false; YM5fyv?  
break; y"Nsh>h  
} a#c6[!  
} ^ns@O+Fk  
if(breakWhile) ZE%
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break; =]k {"?j  
7RZh<A>m  
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//count++; ~axjjv  
//if(count>4) CKA;.sh  
// siteStop(); ^e+
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} fxgr`nC  
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System.err.println("文件下载结束！"); `"%T=w  
} *OQG4aWy  
catch(Exception e){e.printStackTrace ();} OgX6'E\E  
} ETB6f  
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//获得文件长度 < y*x]}  
public long getFileSize() &N3Y|2  
{ Y@ZaJ@%9@  
int nFileLength = -1; xU%w=0z<  
try{ E= `6-H{  
URL url = new URL(siteInfoBean.getSSiteURL()); 1T:Y0  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 6 PxW8pn  
httpConnection.setRequestProperty("User-Agent","NetFox"); @^uH`mc  
8uA,iYD  
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int responseCode=httpConnection.getResponseCode(); ^FnfJ:  
if(responseCode>=400) f-r] |k  
{ p019)X|vx  
processErrorCode(responseCode); 1Z,[|wJ  
return -2; //-2 represent access is error ^Idle*+  
} C)cwAU|h#  
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String sHeader;  TT-h;'nJ  
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for(int i=1;;i++) frBX{L  
{ !Kv@\4  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); O iFS}p  
//Utility.log(in.readLine()); +}-@@,  
sHeader=httpConnection.getHeaderFieldKey(i); Zy_V9j[n  
if(sHeader!=null) M?;y\vS?.  
{ +&["HoKg}&  
if(sHeader.equals("Content-Length")) b=/curl&  
{ Zk[&IBE_  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); JH8zF{?  
break; q7&6r|w1I  
} R<V!%rL;;  
} D$JHs4  
else ~(]0k.\  
break; #Z5}2soA  
} 2ZQ}7`Y  
} C{d7J'Avk  
catch(IOException e){e.printStackTrace ();} u!:z.RH8n  
catch(Exception e){e.printStackTrace ();} 'FYJMIs  
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Utility.log(nFileLength); 2./3 \n2  
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return nFileLength; @9&P~mo/  
} Y \:0Ev  
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P bQk<"J1  
//保存下载信息（文件指针位置） PdVfO8-  
private void write_nPos() GHmv} Z  
{ c,*9K/:  
try{ ?)\a_Tn  
output = new DataOutputStream(new FileOutputStream(tmpFile)); ,()0'h}n  
output.writeInt(nStartPos.length); y1/o^d+@  
for(int i=0;i<nStartPos.length;i++) r0m*5rd1  
{ R-P-i0~  
// output.writeLong(nPos); ]@Sj`J[fd  
output.writeLong(fileSplitterFetch.nStartPos); q
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output.writeLong(fileSplitterFetch.nEndPos); )TmHhNo  
}
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output.close(); "HXYNS>  
} }=!,o  
catch(IOException e){e.printStackTrace ();} )7:J[0ZiQ  
catch(Exception e){e.printStackTrace ();} o`.R!wm:W  
} `N5|Ho*C  
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//读取保存的下载信息（文件指针位置） l|hUw  
private void read_nPos() |{@FMxn|q  
{ B*gdgM*`  
try{ O=9-Qv|  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); %K]euEqs  
int nCount = input.readInt(); pc?>cs8  
nStartPos = new long[nCount]; sp*Vqd  
nEndPos = new long[nCount]; xB !6_VlB  
for(int i=0;i<nStartPos.length;i++) MJ=)v]a  
{ vO;I(^Q  
nStartPos = input.readLong(); CwJDmz\tk  
nEndPos = input.readLong(); Ks\ NE=;5  
} d9n?v)<v  
input.close(); 7G)H.L)$m"  
} PoIl>c1MS  
catch(IOException e){e.printStackTrace ();} 1$
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catch(Exception e){e.printStackTrace ();} b2@VxdFN  
} nW|w
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private void processErrorCode(int nErrorCode) d`1I".y  
{ v<fnB  
System.err.println("Error Code : " + nErrorCode); [NFNzwUB  
} &)oOeRwi].  
&
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//停止文件下载 6&bIXy  
public void siteStop() !a~`Bs$'jr  
{ aTzjm`F0  
bStop = true; ".dZn6"mI  
for(int i=0;i<nStartPos.length;i++) z%/N!RLW  
fileSplitterFetch.splitterStop(); smm
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]
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}(<%`G6N  
} hb{u'=  
}
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//负责部分文件的抓取 N 75:
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**FileSplitterFetch.java `EtS!zD~b  
*/ V_Wwrhua  
package NetFox; #6!52  
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import java.io.*; .I@CS>j  
import java.net.*; H}LS??P  
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public class FileSplitterFetch extends Thread { .SWt3|Pi5  
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String sURL; //File URL 7u[j/l,  
long nStartPos; //File Snippet Start Position
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long nEndPos; //File Snippet End Position 3/#:~a9Q  
int nThreadID; //Thread's ID cJgBI(S5  
boolean bDownOver = false; //Downing is over ,TRTRb;  
boolean bStop = false; //Stop identical $#|gLVOQ  
FileAccessI fileAccessI = null; //File Access interface <94_@3  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException #oJ5k8Wy  
{ ;}z\i  
this.sURL = sURL; u0`%+:]0  
this.nStartPos = nStart; ]qB:PtX  
this.nEndPos = nEnd; *GUAO){'  
nThreadID = id; Yhp]x
  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 bZx!0>h  
} M_LXg%  
*H[Iq!@  
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public void run() P00f6  
{ 6'W[{gzl  
while(nStartPos < nEndPos && !bStop) -TZ p FT"  
{ >]%8Zx[  
}KD;
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try{ a=T
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URL url = new URL(sURL); ?`[NFqv_]  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ~}ET?Q7t  
httpConnection.setRequestProperty("User-Agent","NetFox"); LJVG~Yeo  
String sProperty = "bytes="+nStartPos+"-"; A^2L~g[^Q  
httpConnection.setRequestProperty("RANGE",sProperty); bJ_cId8+  
Utility.log(sProperty); V]S1X^
 
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InputStream input = httpConnection.getInputStream(); U4G}DCU  
//logResponseHead(httpConnection); B??J@+Nf  
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byte[] b = new byte[1024]; na^sBq?\  
int nRead; MuBx#M/  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ouHu8)q'r  
{ _7
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nStartPos += fileAccessI.write(b,0,nRead); `c+/q2M  
//if(nThreadID == 1) Y q
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// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); eh R{X7J  
} A>V
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Utility.log("Thread " + nThreadID + " is over!"); tvd0R$5}  
bDownOver = true; vEQ<A<[Z  
//nPos = fileAccessI.write (b,0,nRead); 
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} vB!|\eJ  
catch(Exception e){e.printStackTrace ();} rd3j1U  
} &:=$wc  
} H.G!A6bd  
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//打印回应的头信息 B}d.#G+_$x  
public void logResponseHead(HttpURLConnection con) &L^CCi  
{ oVCmI"'  
for(int i=1;;i++) I?Q+9Rmm`J  
{ fa.0I~  
String header=con.getHeaderFieldKey(i); F>gmj'-^  
if(header!=null) ESb ]}c:  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); O3V.^_k;  
Utility.log(header+" : "+con.getHeaderField(header)); zdSh:  
else 0iEa[G3  
break; &Np9kIMCB  
} @/%{15s.  
} <5@PWrU?[[  
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2q}..  
public void splitterStop() =8=!Yc(>  
{ hY<{t.ws  
bStop = true; @U -$dw'4  
} +rWZ|&r%  
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} }jSj+*  
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#
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/* ^%y
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**FileAccess.java {F|48P;J  
*//文件访问(定位，写) r+<{S\ Q  
package NetFox; si(;y](  
import java.io.*; uHNpfKnZ  
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y|_Eu:  
public class FileAccessI implements Serializable{ OY"6J@[z  
q;AT>" =)  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 P,bd'  
RandomAccessFile oSavedFile; !NKmx=I]  
long nPos; oN(-rWdhZ  
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public FileAccessI() throws IOException wb"RB A9  
{ rn.\tDeA  
this("",0); u@%|kc`  
} YnV/M,U  
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public FileAccessI(String sName,long nPos) throws IOException >qT'z$  
{ '~-IV0v9  
oSavedFile = new RandomAccessFile(sName,"rw"); h[XGC=%  
this.nPos = nPos; j nwQV  
oSavedFile.seek(nPos); E@ h y7X  
} l54|Q  
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public synchronized int write(byte[] b,int nStart,int nLen) (*l2('e#@  
{ ~tm0QrJn/  
int n = -1; ST8!i`Q$  
try{ 7y*ZXT]f  
oSavedFile.write(b,nStart,nLen); aw}+'(?8]  
n = nLen; \Rk$t
7ZH  
} p*;Qz  
catch(IOException e) "EftN5?/  
{ SlT*C6f  
e.printStackTrace (); =;c_} VY  
} B!aK  
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return n; e-D4'lu  
} F!KV\?eM$  
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} CdhSp$>  
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/* c8'Cq7  
**SiteInfoBean.java 2DMrMmLI  
*/ WBppKj_M  
package NetFox; 5)lW  
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public class SiteInfoBean { 4u:0n>nJ1  
?=
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private String sSiteURL; //Site's URL ~LE[, I:q  
private String sFilePath; //Saved File's Path |ViU4&d*  
private String sFileName; //Saved File's Name rH}fLu8,;Q  
private int nSplitter; //Count of Splited Downloading File C%H9[%k  
oK-!(1A-  
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public SiteInfoBean() , Fytk34  
{//nSplitter的缺省值为5 ! sYf<  
//default value of nSplitter is 5 #w~0uCzQ@  
this("","","",5); B7"Fp  
} :Z2tig nL  
jL4>A$  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) ,hE/II`-d'  
{ _p4}<pG  
sSiteURL= sURL; 8j\d~Lw=  
sFilePath = sPath; g{DFS[h  
sFileName = sName; 0o68rF5^s  
this.nSplitter = nSpiltter; cgNt_8qC  
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} $Qq_qTJu?G  
 ~u/@rqF  
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public String getSSiteURL() IrO+5w  
{ M]ap:  
return sSiteURL; u:4["ViC  
} tyXl}$)y  
( Yi=v'd  
2YIF=YWO},  
public void setSSiteURL(String value) Oc-u=K,B  
{ /VtlG+dLl  
sSiteURL = value; w4OW4J#  
} UA0tFeH  
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public String getSFilePath() U?6yke  
{ ^uBwj}6  
return sFilePath; i/:5jI|  
} +v1-.z  
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public void setSFilePath(String value) {W'8T}q  
{ 6e:P.HqjA  
sFilePath = value; .v7`$(T  
} 6~:+:;  
>x?2Fz.  
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public String getSFileName() "w^Nu6  
{ & >b+loF  
return sFileName; 4.k`[q8  
} BA`:miH<  
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public void setSFileName(String value) <%rh/r  
{ qhwoV4@f  
sFileName = value; kC|Tubs(  
} z"av|(?d  
d qpgf@  
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public int getNSplitter() G:hU{S7  
{ {tmKCG  
return nSplitter; ,]U[W  
} GRQ_+K  
n>T:
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public void setNSplitter(int nCount) NE[y|/  
{ 0&B:\  
nSplitter = nCount; YME[%c2x  
} >@:667i,`  
} y;,
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/* :B+Rg cqi  
**Utility.java To^# 0  
*/ /THNP 8.  
package NetFox; 59K}  
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public class Utility { a G@nErdW  
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public Utility() 9IOGc}  
{ }"0{zrz  
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} zw< 4G[u  
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//线程睡眠 5<^'Cy
 
public static void sleep(int nSecond) \{:%v#ZZ  
{ 1ThwvF%Qo  
try{ }!=gP.Zu^  
Thread.sleep(nSecond); {Wa~}1`Kl  
} psu OJ-  
catch(Exception e) y]<#%Fh  
{ Wge ho  
e.printStackTrace (); hRRkFz/0&  
} *3P3M}3~\  
} HIsB|  
@kz!{g]Sn  
//日志 ~JAjr(G#o  
public static void log(String sMsg) /=q.tDH=I  
{ F G3Sk!O6  
System.err.println(sMsg); e& p_f<  
} @~s~/[  

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public static void log(int sMsg) d&5c_6oW  
{ >6IXuq  
System.err.println(sMsg); /MhS=gVxM  
} ?Q;kZmQl  
} f.J9) lfb  
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+8^5C,V  
/* !e&rVoA  
**TestMethod.java 2+,5p  
*/ |7]?>-  
package NetFox; J"5jy$30'$  
=w?M_[&K)  
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public class TestMethod { zuk"  
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RZW$!tyI=  
public TestMethod() %3rTQ:X
 
{ ///xx/weblogic60b2_win.exe r)OO&. P@j  
try{ oPCrD.s  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); FOeVRq:#  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); qFrt^+@  
SiteFileFetch fileFetch = new SiteFileFetch(bean); "/Om}*VhD  
fileFetch.start(); sw[oQ!f  
}
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catch(Exception e){e.printStackTrace ();} hHCzj*5  
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} o>@=N2n  
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public static void main(String[] args) >6OCKl  
{ sTt9'P`  
new TestMethod(); Ze#Jhn@  
} Ir!2^:]!  
} ] xb]8]  
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