http断点续传简单实现（java)

/* CfoT$g  
**SiteFileFetch.java Qyr^\a;k'  
*/ ersddb^J]  
package NetFox; Rs<li\GS  
import java.io.*; o0Y {k8  
import java.net.*; m4.IaBn/  
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public class SiteFileFetch extends Thread { a.r+>44M  
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SiteInfoBean siteInfoBean = null; //文件信息Bean Qb}1tn)  
long[] nStartPos; //开始位置 n9}3>~ll  
long[] nEndPos; //结束位置 gxS*rzCG  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 0Y8Si^T  
long nFileLength; //文件长度 Wu\{)g{&  
boolean bFirst = true; //是否第一次取文件 fP>*EDn@xg  
boolean bStop = false; //停止标志 H +O7+=&  
File tmpFile; //文件下载的临时信息 DRC2U%[  
DataOutputStream output; //输出到文件的输出流 A3VXh^y+  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） c5& _'&  
public SiteFileFetch(SiteInfoBean bean) throws IOException Dl2`b">u  
{ Bn 5]{Df  
siteInfoBean = bean; Ov$_Phm:  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); lC8DhRd0_  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 6^M!p4$hF  
if(tmpFile.exists ()) ^Gc#D:zU  
{ ,,hW|CmN30  
bFirst = false; -hx' T6G%  
read_nPos(); h7iI=[_V  
} %. =B=*  
else iB
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{ '+6Sk
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nStartPos = new long[bean.getNSplitter()]; ^{3,ok*Nf  
nEndPos = new long[bean.getNSplitter()]; 9U[ A   
} Bw]Y71  
+}
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} UQmdm$.  
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public void run() %jgB
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{ $wgHaSni  
//获得文件长度 Sz.sX w;  
//分割文件 8Z{e/wnVF  
//实例FileSplitterFetch uTgvMkO  
//启动FileSplitterFetch线程 Cpm&w?6  
//等待子线程返回 <6_RWtU  
try{ T)ZO+}  
if(bFirst) 21b  
{ K+=cNC4B  
nFileLength = getFileSize(); vhA4ol  
if(nFileLength == -1) 0}a="`p#<  
{ >h?!6L- d  
System.err.println("File Length is not known!"); PyOj{WX>W  
} n&? --9r  
else if(nFileLength == -2) D<-MbK^S  
{ ^W&qTSjh  
System.err.println("File is not access!"); 9~ [Sio~  
} >}& :y{z~  
else jF5Y-CX  
{ ^EK]z8;|  
for(int i=0;i<nStartPos.length;i++) A2fc_A/a  
{ v{/z`J!JR  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); sp=;i8Y 3  
} 8.9Z0  
for(int i=0;i<nEndPos.length-1;i++) tVB9kxtE  
{ C,2k W`[V  
nEndPos = nStartPos[i+1]; 0+\%os V  
} zGDLF`  
nEndPos[nEndPos.length-1] = nFileLength; ws!pp\F  
} c7~+5  
} : MfY8P)  
-@6R`m=>  
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//启动子线程 )=KD  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; Hs}3c R}  
for(int i=0;i<nStartPos.length;i++) gj(|#n5C  
{ Fx6c*KNX3  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), =l7@YCj5c  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), ?X'm>R. @  
nStartPos,nEndPos,i); 2pKkg>/S  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); G?p !*7N  
fileSplitterFetch.start(); rb"J{^  
} =;hz,+  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), it Byw1/  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); us/}_r74N*  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", ULqFJ*nla  
nEndPos = " + nFileLength); Oz3JMZe  
// fileSplitterFetch[nPos.length-1].start(); ~F gxhK2+  
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X+0+
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//等待子线程结束 re]e4lZ  
//int count = 0; }0Q_yuzx0m  
//是否结束while循环 S!'
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boolean breakWhile = false; V 6DWYs>  
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while(!bStop) eflmD$]SW  
{ J>@T'#  
write_nPos(); 9L2]PU v  
Utility.sleep(500); >s5i  
breakWhile = true; i?{cB!7  
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for(int i=0;i<nStartPos.length;i++) 8>\tD  
{ /0.m|Th'm  
if(!fileSplitterFetch.bDownOver) A_:CGtv:  
{ 8h,>f#)0c  
breakWhile = false; 8-s7^*!  
break;

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} &xAwk-{W  
} xaPaK-  
if(breakWhile) L
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break; `>i8$q%  
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50<QF  
//count++; QPc4bg\J~t  
//if(count>4) ZOAHM1ci  
// siteStop(); e-Pn,j  
} <"GgqyRzv  

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System.err.println("文件下载结束！"); F,[GdE;P  
} (uW$ch@2K  
catch(Exception e){e.printStackTrace ();} "!g}Q*  
} |TQ#[9C0  
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})V^t3  
//获得文件长度 !_yWe  
public long getFileSize() e&R?9z-*  
{ S)?V;@p6  
int nFileLength = -1; SS)9+0$  
try{ IonphTcU!  
URL url = new URL(siteInfoBean.getSSiteURL()); n'5LY9"  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ZH~=;S-t  
httpConnection.setRequestProperty("User-Agent","NetFox"); k_o$ Ci  
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int responseCode=httpConnection.getResponseCode(); ^\(<s  
if(responseCode>=400) SsY:gp_  
{ eBZ94rA]  
processErrorCode(responseCode); ;4:[kv@  
return -2; //-2 represent access is error >bLhCgF:"  
} pO_$8=G+  
;h7W(NO~z  
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String sHeader; 6zZT5 Kn  
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for(int i=1;;i++) xlP0?Y1Bl  
{ K Y=$RO  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); (:9=M5d  
//Utility.log(in.readLine()); PxvD0GTW  
sHeader=httpConnection.getHeaderFieldKey(i); 'PS_|zI  
if(sHeader!=null) p.ks jD  
{ j*6>{_[  
if(sHeader.equals("Content-Length")) wni^qs.i@3  
{ J4woZ{d  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); A)5;ae  
break; .7<6 zG6J  
} ?niv}/'%O  
} O30eq 7(  
else )` ^/Dj;  
break; 2gN78
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} .rcXx
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} |uIgZ|7[  
catch(IOException e){e.printStackTrace ();} ,SF>$ .  
catch(Exception e){e.printStackTrace ();} gb^<6BYUG  
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VE $Kdo^  
Utility.log(nFileLength); %7S{g  
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return nFileLength; hWz/PK,  
} r+W;}nyf  
'44I}[cA/  
 r .`&z  
//保存下载信息（文件指针位置） Nf^6t1se  
private void write_nPos() cHAq[Ebp2!  
{ }~+q S`  
try{ 8o  SL3  
output = new DataOutputStream(new FileOutputStream(tmpFile)); c!ul9Cw  
output.writeInt(nStartPos.length); 8=-/0y9,  
for(int i=0;i<nStartPos.length;i++) [W8"Mc|ve  
{ tt03gU`  
// output.writeLong(nPos); qy( kb(J  
output.writeLong(fileSplitterFetch.nStartPos); Jwtt&" c0.  
output.writeLong(fileSplitterFetch.nEndPos); B;A< pNT  
} C9j3|]nyL  
output.close(); L2Z-seE  
} |I2~@RfpO:  
catch(IOException e){e.printStackTrace ();} Ywo
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catch(Exception e){e.printStackTrace ();} MFtC2*
 
} k+
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S] R.:T_%  
//读取保存的下载信息（文件指针位置） E5X#9;U8E"  
private void read_nPos() !<UdG+iV  
{ fAT+x1J\  
try{ *JA0Vs5  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); #GfM!<q<  
int nCount = input.readInt(); 6 9s%  
nStartPos = new long[nCount]; BmI'XB3'P  
nEndPos = new long[nCount]; <Em|0hth  
for(int i=0;i<nStartPos.length;i++) b^'>XT~1J&  
{ 5@nvcCp  
nStartPos = input.readLong(); .)
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nEndPos = input.readLong(); nhLw&V3y  
} \^3cN
w  
input.close(); @M)"  
} FwpTQix!  
catch(IOException e){e.printStackTrace ();} q71V]!  
catch(Exception e){e.printStackTrace ();} m0,TH[HWGF  
} ~(-df>  
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private void processErrorCode(int nErrorCode) G<FB:?|  
{ FfM,~s<Efz  
System.err.println("Error Code : " + nErrorCode); v@1f,d  
} vVFT0_  
;XI=Y"h{%  
c{{RP6o/j=  
//停止文件下载 q!
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public void siteStop() C,) e7  
{ +EvY-mwfQ  
bStop = true; -1%AM40j  
for(int i=0;i<nStartPos.length;i++) m+EtB6r  
fileSplitterFetch.splitterStop(); Kwo0%2Onkd  
@ [<B:Tqo  
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} 0[92&:c,  
} =p \eh?^  
//负责部分文件的抓取 |!xqkmX  
**FileSplitterFetch.java 4p&YhV7j)o  
*/ t]XF*fZH  
package NetFox; |HQFqa<  
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import java.io.*; yhxZ^(I  
import java.net.*; [-hsG E  
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public class FileSplitterFetch extends Thread { ^o[(F<q  
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String sURL; //File URL S20E}bS:>  
long nStartPos; //File Snippet Start Position 7,2#0Z`ge  
long nEndPos; //File Snippet End Position >_u5"&q  
int nThreadID; //Thread's ID DxzNg_E]  
boolean bDownOver = false; //Downing is over "64D.c(r$  
boolean bStop = false; //Stop identical hOr4C4  
FileAccessI fileAccessI = null; //File Access interface <(x!P=NM-  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException xX\A&9m  
{ c#T0n !}  
this.sURL = sURL; Ht7v+lY90^  
this.nStartPos = nStart; 9@8)ZHf  
this.nEndPos = nEnd; GQ1m h*4$  
nThreadID = id; _MzdbUb5,  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 gjPbhY=C[  
} gacE?bW'  
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public void run() BF(Kaf;<t.  
{ PaBqv]  
while(nStartPos < nEndPos && !bStop) dk@iAL*v  
{ Rqun}v}  
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try{ f4+}k GJN  
URL url = new URL(sURL); &h?8yV4B  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Dlx-mm_  
httpConnection.setRequestProperty("User-Agent","NetFox"); ^e:rRk7 &  
String sProperty = "bytes="+nStartPos+"-"; M%N_4j
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httpConnection.setRequestProperty("RANGE",sProperty); K~jN"ev  
Utility.log(sProperty); E)%r}4u>  
{p7b\=WB-  
nm !H&#<  
InputStream input = httpConnection.getInputStream(); 3.D|xE]g  
//logResponseHead(httpConnection); OIrr'uNH  
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byte[] b = new byte[1024]; oU)HxV  
int nRead;
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while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ziG]BZ  
{ S3Sn_zqG  
nStartPos += fileAccessI.write(b,0,nRead); Kz9h{Tu4  
//if(nThreadID == 1) IK|W^hH\8  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); LO;Z3Q>#0  
} RLUH[[  
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Utility.log("Thread " + nThreadID + " is over!"); zHt}`>y&  
bDownOver = true; AGgL`sP  
//nPos = fileAccessI.write (b,0,nRead); zK ir  
} %( o[Hsl  
catch(Exception e){e.printStackTrace ();} GFO(O  
} #)28ESj  
} 0?\d%J!"S  
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//打印回应的头信息 D(^ |'1  
public void logResponseHead(HttpURLConnection con) ~
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{
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for(int i=1;;i++) ^*+-0b;[G  
{ .="[In'  
String header=con.getHeaderFieldKey(i); w\Bx=a>vc  
if(header!=null) ^]
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//responseHeaders.put(header,httpConnection.getHeaderField(header)); `|g*T~; kC  
Utility.log(header+" : "+con.getHeaderField(header)); O-YB+~"3Z  
else ]5hGSl2  
break; zoO9N oUHW  
} O^I%Xk  
} 2ZZF hj  
]{E
{ IW8  
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public void splitterStop() <P)0Yu  
{ X~5kgq0"  
bStop = true; +]NPxUa  
} `DcZpd.n  
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} O(Vi/r2:e  
} l4d/I  
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/* d&[.=M\E8  
**FileAccess.java Ex3V[v+D(  
*//文件访问(定位，写) @&E{ L  
package NetFox; }!0nb)kL  
import java.io.*; 
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public class FileAccessI implements Serializable{ b|z_1j6U  
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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 ILq"/S.  
RandomAccessFile oSavedFile; +x"cWOg  
long nPos; YJEL'k<l  
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public FileAccessI() throws IOException 6Y(Vs>  
{ 0(~,U!g[=  
this("",0); 3-Xc3A=w  
} C!r9+z)<  
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public FileAccessI(String sName,long nPos) throws IOException KZ}F1Mr  
{ <!M ab}  
oSavedFile = new RandomAccessFile(sName,"rw"); 6
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this.nPos = nPos; -H;p +XAY  
oSavedFile.seek(nPos); ]$gBX=  
} 4)=\5wJDg1  
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public synchronized int write(byte[] b,int nStart,int nLen) muqIh!nn  
{ =
7WE   
int n = -1; 09>lx$  
try{ 3d0Yq  
oSavedFile.write(b,nStart,nLen); (e$/@3*  
n = nLen; C/L+:b&x~  
} p|b&hgA  
catch(IOException e) [$b\#{shtP  
{ U~e^  
e.printStackTrace (); Z>#MTxU(  
} O-ZB4hN8  
|p1pa4%}  
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return n; `]xot8  
} v<qiu>sbz}  
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} 9O/l{  
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/* 8O5@FU 3  
**SiteInfoBean.java _4VS.~}/R  
*/ + ^9;<>P  
package NetFox; i
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public class SiteInfoBean { @Yy:MdREA  
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private String sSiteURL; //Site's URL ped3}i+|]  
private String sFilePath; //Saved File's Path K&WNtk3hT  
private String sFileName; //Saved File's Name jGtoc,\X
 
private int nSplitter; //Count of Splited Downloading File JyBsOC3  

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public SiteInfoBean() '0!IF&p'  
{//nSplitter的缺省值为5 jJmg9&^R  
//default value of nSplitter is 5 {,|
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this("","","",5); #!%\97ZR  
} }m~2[5q%/  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) P|S'MS';:  
{ mne=9/sE"  
sSiteURL= sURL; n./onv  
sFilePath = sPath; E Fx@O  
sFileName = sName; y ~ A]  
this.nSplitter = nSpiltter; f;(]P  
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} I oz rZ  
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public String getSSiteURL() k-(hJ}N  
{ ?'_Q^O>  
return sSiteURL; Y(D@B|"'m  
} #]yb;L  
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public void setSSiteURL(String value) ZR3x;$I~4  
{ #0HF7C3  
sSiteURL = value; ,'CDKzY  
} =~&Fq$$  
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public String getSFilePath() $h Isab_  
{ Z' 0Gd@/  
return sFilePath; I499Rrw#E  
} a/.O,&3  
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public void setSFilePath(String value) VK+#!!Ha  
{ z^/aJ@gQ  
sFilePath = value; P^%.7C  
} -4p^wNR  
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public String getSFileName() h-1eDxK6  
{  _"ysJ&  
return sFileName; \jdpL1  
} EiY i<Z_S  
urHQb5|T}  
/hue]ZaQq  
public void setSFileName(String value) *R*Tmo"  
{ Ah_'.r1<P9  
sFileName = value; #]ii/Et#x  
} ?Rl?Pp=>  
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public int getNSplitter() -v9V/LJ  
{ `@{qnCNQ  
return nSplitter; $cev,OW6]  
} 9-+6Ed^2  
x C'>W"pY  
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public void setNSplitter(int nCount) 63QS
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{ a$I; L  
nSplitter = nCount; $S$%avRX  
} Aa&3x~3+  
} 5Mb1==/R  
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/* r4O*0Q_  
**Utility.java ?-O(EY1E  
*/ S ~lw5  
package NetFox; uU`zbh}]L.  
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public class Utility { S<Q6b_D  
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w
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public Utility() au8bEw&W  
{ -t %.I=|  
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} ^HKxaW9W  
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//线程睡眠 p&bQ_XOH  
public static void sleep(int nSecond) 4qjY,QJ  
{ C+}uH:I'L  
try{ J3Q.6e=7  
Thread.sleep(nSecond); SSi}1  
} (@`+Le  
catch(Exception e) yPm)r2Ck  
{ xYM!mcA  
e.printStackTrace (); SZc6=^$  
} m%q#x8Fp  
} A0S6 4(  
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//日志 -4b9(  
public static void log(String sMsg) Yc#oGCt  
{ XaD}J:Xq  
System.err.println(sMsg); BZsw(l4/0'  
} bn^^|i  
;4XX8W1  
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public static void log(int sMsg) ~@R=]l"  
{ %@*diJ  
System.err.println(sMsg); hdN3r{  
} ~9]tt\jN*Y  
} O>w
$  
2N(c&Dzkh`  
t,R5FoV  
/* <H)h+?&~d  
**TestMethod.java ,[+gE\z{{u  
*/ vC\]7]mC  
package NetFox; b#k$/A@  
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L<QqQ"`  
public class TestMethod { t ba%L  
X>F/0/  
sBF}j.b  
public TestMethod() [F+lVb  
{ ///xx/weblogic60b2_win.exe Wuye:b!  
try{ /5
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SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); mRfF)  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); rtf>\j+  
SiteFileFetch fileFetch = new SiteFileFetch(bean); :?jOts>uP  
fileFetch.start(); suPQlU>2sj  
} Z\i@Qa+r  
catch(Exception e){e.printStackTrace ();} 0?SdAF[:z  
ctdV4%^{  
SLz^Wg
._  
} *8js{G0h  
9+=U&*  
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public static void main(String[] args) sqac>v  
{ &^qD<eZ!Eq  
new TestMethod(); #)=P/N1  
} &{y-}[~  
} )#Y*]  
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