http断点续传简单实现（java)

/* O@a7MzJ  
**SiteFileFetch.java =g$%jM>35  
*/ i93^E~q]  
package NetFox; Q+*@!s  
import java.io.*; ?8YbTn1f)  
import java.net.*; ,6aF~p;wI|  
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public class SiteFileFetch extends Thread { JZ/T:Hsh4  
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SiteInfoBean siteInfoBean = null; //文件信息Bean M=4`^.Ocm  
long[] nStartPos; //开始位置 ; jrmr`l=  
long[] nEndPos; //结束位置 >3&9Wbv>  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 m2[J5n?zLL  
long nFileLength; //文件长度 /|@~:5R5H  
boolean bFirst = true; //是否第一次取文件 ;&XC*R+  
boolean bStop = false; //停止标志 ohi0_mBz  
File tmpFile; //文件下载的临时信息 c9Q_Qr0'  
DataOutputStream output; //输出到文件的输出流 *RFBLCt  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） uG(XbDZZ1W  
public SiteFileFetch(SiteInfoBean bean) throws IOException P?+ VR=t  
{ .:=5|0m  
siteInfoBean = bean; ]>[0DX]j  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); w{ Pl  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); [X ]XH  
if(tmpFile.exists ()) <(l`zLf4p  
{ lqvP Dz  
bFirst = false; !J[!i"e  
read_nPos(); :VE0eJ]J6  
} czH# ~  
else 'ql<R0g  
{ NMESGNa)z  
nStartPos = new long[bean.getNSplitter()]; }O2P>Z?V  
nEndPos = new long[bean.getNSplitter()]; bSa]={}L(  
} bd[iD?epD]  
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} iB
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y w:=$e5  
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public void run() i:H]Sb)<b  
{ 9Dd`x7$a  
//获得文件长度 @/xdWN!,  
//分割文件 j|@8Vx
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//实例FileSplitterFetch {Rn*)D9  
//启动FileSplitterFetch线程 E5Lq-   
//等待子线程返回 [XkWPx`  
try{ 3U*4E?g  
if(bFirst) L;fz7?_j  
{ P>Ru  
nFileLength = getFileSize(); M-(,*6Q  
if(nFileLength == -1) 7A{Z1[7  
{ \mqrDaB  
System.err.println("File Length is not known!"); n!U1cB{  
} ;rl61d}NH#  
else if(nFileLength == -2) Nhtc^DX  
{ n>,? V3ly  
System.err.println("File is not access!"); k=X)axt1  
} d"S\j@  
else 6iY(RYZ7-  
{ KON^  
for(int i=0;i<nStartPos.length;i++) P`y.3aK  
{ >RrG&W
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nStartPos = (long)(i*(nFileLength/nStartPos.length)); 10_>EY`  
} uJa.]J~L=  
for(int i=0;i<nEndPos.length-1;i++) @*WrHoa2N  
{ +9M";'\c  
nEndPos = nStartPos[i+1]; 10tTV3`IM  
} Wr8}=\/  
nEndPos[nEndPos.length-1] = nFileLength; @B!gxW\C  
} 'fZ\uMdTx  
} rpEN\S%7P  
&&C'\,ZK5  
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//启动子线程 JO~62='J  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 7_J0[C!G  
for(int i=0;i<nStartPos.length;i++) 6Q_ZP#oAV  
{ {uxTgX  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(),
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), xrkR)~ E  
nStartPos,nEndPos,i); !1l~'/r  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); GyfKSj;  
fileSplitterFetch.start(); >b8-v~o{  
} 5+t$4N+P  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), h r6?9RJY  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); #P {|7}jk  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", T>,[V:  
nEndPos = " + nFileLength); &,* ILz  
// fileSplitterFetch[nPos.length-1].start(); 27MwZz  
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^_BjO(b'e  
//等待子线程结束 BCX2C  
//int count = 0; (IIZvCek  
//是否结束while循环 DXZZZ[#  
boolean breakWhile = false; ,lVQ-qw5  
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while(!bStop) BE!l{  
{ Y/ %XkDC~  
write_nPos(); )!;20Po  
Utility.sleep(500); >` u8(  
breakWhile = true; c GyBml1  
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o ^ 08<  
for(int i=0;i<nStartPos.length;i++) j.c{%UYj  
{ Uy?X-"UR  
if(!fileSplitterFetch.bDownOver) M^G9t*I  
{ &AVX03P  
breakWhile = false; #k,.xMJ~  
break; (Dn1Eov  
} kV4L4yE  
} $"va8,  
if(breakWhile) <YrsS-9  
break; bmh@SB  
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ux)Wh.5  
//count++; +W8kMuM!  
//if(count>4) Hm+VGH'H?  
// siteStop(); 2'Raj'2S4  
} }0]iS8*tL  
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System.err.println("文件下载结束！"); @X P_~ N  
} .pH 4[~  
catch(Exception e){e.printStackTrace ();} /?a9g>G%N  
} )(pgJLW  
I1JL`\;4  
]C{N4Ni^Z  
//获得文件长度 9t8ccr  
public long getFileSize() =%|f-x  
{ ZA}!Rzo  
int nFileLength = -1; i8%Z(@_`  
try{ <[=[|DS l  
URL url = new URL(siteInfoBean.getSSiteURL()); 8C*xrg#g:  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); sX
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httpConnection.setRequestProperty("User-Agent","NetFox"); 5C9 .h:c4y  
rS+ >oP}  
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int responseCode=httpConnection.getResponseCode(); ZgmK~iJ  
if(responseCode>=400) {fY(zHC  
{ XW+-E^d  
processErrorCode(responseCode); X|L
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return -2; //-2 represent access is error fw|t`mUGu  
} IDdu2HNu  
[Sc
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String sHeader;
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for(int i=1;;i++) h7S; 4]  
{ W#kLM\2L  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 8E>2 6@.  
//Utility.log(in.readLine()); !/1~  
sHeader=httpConnection.getHeaderFieldKey(i); O#<S\66  
if(sHeader!=null) y^D3}ds  
{ Z=l2Po n  
if(sHeader.equals("Content-Length")) ^ '_Fd  
{ a(uQGyr[k1  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); ?OGs+G  
break; IvI;Q0E-3  
} Z/:W.*u  
}
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else Kr`.q:0GK  
break; ca[*#xiJ  
} fT=ZiHJ3Gu  
} .5tXwxad"  
catch(IOException e){e.printStackTrace ();} W k"_lJ  
catch(Exception e){e.printStackTrace ();} `.wgRUhFH;  
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Utility.log(nFileLength); mA#^Pv*  
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return nFileLength; >n1UK5QD  
} |=W>4>  
[P]M)vJ**  
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//保存下载信息（文件指针位置） c~6ywuq+M`  
private void write_nPos() {@s6ly].  
{ $
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try{ tq*{Hil>P`  
output = new DataOutputStream(new FileOutputStream(tmpFile)); ;cb='s  
output.writeInt(nStartPos.length); [?da BXS  
for(int i=0;i<nStartPos.length;i++) :ra[e(l9  
{ [p)2!]y  
// output.writeLong(nPos); y }h2
  
output.writeLong(fileSplitterFetch.nStartPos); 7e{w,.ny!  
output.writeLong(fileSplitterFetch.nEndPos); 2(GLc*B>  
} =wa5\p/  
output.close(); -CPLgT  
} FH;)5GGnv  
catch(IOException e){e.printStackTrace ();} fQw|SW  
catch(Exception e){e.printStackTrace ();} Eb8z`@p  
} GB}X
 
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//读取保存的下载信息（文件指针位置） ul"Z% 1]  
private void read_nPos() QdIoK7J 9  
{ zeH=py[n  
try{ "eI">`!g  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); l_fERp#y  
int nCount = input.readInt(); f&XM|Bg  
nStartPos = new long[nCount]; 0b2;  
nEndPos = new long[nCount]; eqpnh^0}d  
for(int i=0;i<nStartPos.length;i++) iT1HbAT]  
{ |~=4ZrcCP  
nStartPos = input.readLong(); UQtG<W]<  
nEndPos = input.readLong(); d"+ _`d=`  
} 0%3T'N%  
input.close(); WhV>]B2+"  
} 1i Q(q\%  
catch(IOException e){e.printStackTrace ();} 5zt5]zl'  
catch(Exception e){e.printStackTrace ();} g$8aB{)  
} "azrcC  
"||G`%aO+t  
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private void processErrorCode(int nErrorCode) RP wP4Z  
{ X<H+Z2d  
System.err.println("Error Code : " + nErrorCode); m h|HEkM  
} fJY b)sN  
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> 'JWW*Y!  
//停止文件下载 k59.O~0V  
public void siteStop() >k u7{1)  
{ IZ]L.0,  
bStop = true; ML X: S?  
for(int i=0;i<nStartPos.length;i++) oXqx]@7  
fileSplitterFetch.splitterStop(); fy!,cK};  
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} ;giT[
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} |U="B4  
//负责部分文件的抓取 td2bL4  
**FileSplitterFetch.java y(Q.uYz*  
*/ [_p&,$z8[  
package NetFox;
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import java.io.*; y;HJ"5.Mw  
import java.net.*; 4$v08zZ  
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public class FileSplitterFetch extends Thread { f&Mei
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String sURL; //File URL OH~I+=}.  
long nStartPos; //File Snippet Start Position m*TJ@gI*t  
long nEndPos; //File Snippet End Position [zl"G^z  
int nThreadID; //Thread's ID PPNZ(j  
boolean bDownOver = false; //Downing is over q.RW_t~  
boolean bStop = false; //Stop identical QBT_H"[  
FileAccessI fileAccessI = null; //File Access interface ]b@:?DX8  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException MbC&u:@ "v  
{ &v_b7h  
this.sURL = sURL; {I"d"'h  
this.nStartPos = nStart; <' b%  
this.nEndPos = nEnd; HoKN<w  
nThreadID = id; +JL"Z4b@R}  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 FYeUz$/  
} `)eqTeW  
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public void run() gOA]..lh  
{ *AN2&>Y  
while(nStartPos < nEndPos && !bStop) Z9 tjo1X  
{ KRP)y{~o  
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try{ ]]bL;vlw  
URL url = new URL(sURL); v\ Xk6k  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); <lVW;l7  
httpConnection.setRequestProperty("User-Agent","NetFox"); i6h , Aw3  
String sProperty = "bytes="+nStartPos+"-"; ||k^pzj%  
httpConnection.setRequestProperty("RANGE",sProperty); ]#x?[F  
Utility.log(sProperty); B(dq$+4  
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InputStream input = httpConnection.getInputStream(); *1;}c z  
//logResponseHead(httpConnection); Wtwh.\Jba  
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byte[] b = new byte[1024]; 9l:Bum)9  
int nRead; ``mW\=fe  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) #x|h@(y|  
{ NEh5   
nStartPos += fileAccessI.write(b,0,nRead); u4[3JI>  
//if(nThreadID == 1) O486:tF  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); *.9.BD9  
} X+T +y>ea  
I8 {2cM;  
9:tKRN_D  
Utility.log("Thread " + nThreadID + " is over!"); w/HGmVa  
bDownOver = true; E6d0YgfD  
//nPos = fileAccessI.write (b,0,nRead); t,K_!-HX+  
} ?Y#0Je
 
catch(Exception e){e.printStackTrace ();} ,-*oc>  
} '\X<+Sm'  
} ef=LPCi?  
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//打印回应的头信息 @cZNoD  
public void logResponseHead(HttpURLConnection con) Yxt`Uvc(^h  
{ YQ}bG{V  
for(int i=1;;i++) I
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{ P=V=\T<4_  
String header=con.getHeaderFieldKey(i); )0JXUC e  
if(header!=null) dF%sD|<)  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); %Ot^G%34  
Utility.log(header+" : "+con.getHeaderField(header)); @OlV6M;qJ  
else w%[`'_[  
break; T7=~l)I  
} agFWye  
} 3g]Sp/  
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public void splitterStop() p}NIZ)]$  
{ *a7&v3X  
bStop = true; u@$C i/J*  
} 'i|z>si[*  
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} +SSF=]4+  
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/* q|. X[~e|  
**FileAccess.java FU|c[u|z  
*//文件访问(定位，写)
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package NetFox; 8ctUK|
 
import java.io.*; F$FCfP7  
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public class FileAccessI implements Serializable{ }F1|& A  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 MeqW/!72$L  
RandomAccessFile oSavedFile; 40}8EP k)  
long nPos; UJ_E&7,L  
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public FileAccessI() throws IOException [}|-%4s  
{ sV/#P<9  
this("",0); 42?X)n>  
} Pgs^#(^>  
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public FileAccessI(String sName,long nPos) throws IOException '~3a(1@8  
{ `}KK@(Y  
oSavedFile = new RandomAccessFile(sName,"rw"); h*f=  
this.nPos = nPos;
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oSavedFile.seek(nPos); =~% B}T  
} >WMH.5p  
rHu#  
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public synchronized int write(byte[] b,int nStart,int nLen) !Jw   
{ /H=fK  
int n = -1; )FM
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try{ l|`%FB^k  
oSavedFile.write(b,nStart,nLen); UB
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n = nLen; &_ Ewu@4  
} lM C4j  
catch(IOException e) u2^oXl  
{ ]BU,*YaB  
e.printStackTrace (); ik77i?Hg  
} &3mseU  
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return n; UK2Y<\vD  
} x"~F=jT  
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} P$Y< g/s4  
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/* @6>R/]  
**SiteInfoBean.java I.j`h2  
*/ pr.Vfb  
package NetFox; m,v"N%k,  
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public class SiteInfoBean { eP-q[U?$n  
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private String sSiteURL; //Site's URL ^:K"Tv.=  
private String sFilePath; //Saved File's Path !'Xk=+  
private String sFileName; //Saved File's Name zr?%k]A%UO  
private int nSplitter; //Count of Splited Downloading File v
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fR}|CP  
.e5GJAW~9  
public SiteInfoBean() _r5Q%8J  
{//nSplitter的缺省值为5 59O;`y0  
//default value of nSplitter is 5 WEUr;
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this("","","",5); |S
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} g>x2[//pk  
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/] ce?PPC  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) _CPe  
{ "-kb=fY  
sSiteURL= sURL; Z$Ynar  
sFilePath = sPath; Y4}!9x  
sFileName = sName; D{h1"q  
this.nSplitter = nSpiltter; T{bM/?g
 
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} f.rz2)o  
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public String getSSiteURL() a_m P$4T  
{ ~" B0P>7  
return sSiteURL; s d>&6R^  
} xj)*K
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R~CQ=KQ.  
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public void setSSiteURL(String value) q*TH),)J  
{ 9M:wUYHT  
sSiteURL = value; FD*`$.e3\  
} *j2P#et  
xaX3<V@S  
}]N7CWy  
public String getSFilePath() *Eu ca~%=  
{ ,<%Y.x%4z[  
return sFilePath; `#A&v  
}  W *0XV  
`UMv#-Y8  
b-ULoV  
public void setSFilePath(String value) BbA>1#i5]  
{ 1j# ~:=I  
sFilePath = value; Lg[*P8wE  
} Zaf].R  
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public String getSFileName() a Umcs!@  
{ J2Ocf&y;  
return sFileName; RD_&m?d  
} R{\vOw:*  
C;}~C:aJ  
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public void setSFileName(String value) E:T<mI?d  
{
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sFileName = value; ~4'e)g.hG  
} >,Zjlkh3  
C,hs!v6  
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public int getNSplitter() }k.-xaj  
{ L
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return nSplitter; &OK(6o2m;  
} X{P_HCd  
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public void setNSplitter(int nCount) SfyZ,0  
{ DGj:qd(  
nSplitter = nCount; _W/s=pCh  
} fySzZ  
} mEv<r6qDT  
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/* _N$3c<dY'  
**Utility.java z 3fS+x:E{  
*/ [!,&A{.!  
package NetFox; c<wsWs 4V  
r#JE7uneT  
++-HdSHY  
public class Utility { nZ>qM]">u  
/+.Bc(`  
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public Utility() @X?DHLM  
{ QUVwO m  
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d
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} fAm^-uq[  
z4b2t}  
//线程睡眠 rQ(Aj  
public static void sleep(int nSecond) B/:q  
{ !JzM<
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try{ fchsn*R%-  
Thread.sleep(nSecond); Ii%^z?'  
} B BbGq8p  
catch(Exception e) 6!bVPIyYO  
{ ]@vX4G/  
e.printStackTrace (); @AaM]?=P{  
} bdZ[`uMD  
} *%7[{Loz  
 gPh;  
//日志 No>XRG+  
public static void log(String sMsg) XxcY  
{ m.pB]yq&  
System.err.println(sMsg); jB!p,fqcb  
} ^.p({6H  
Zy|B~.@<j  
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public static void log(int sMsg) x2=Bu#Y  
{ x^Q:U1  
System.err.println(sMsg); H<#M)8  
} bGOOC?[UX  
} /W1!mih  
t6m3lq{  
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/* '#!nK O2<  
**TestMethod.java y^zII5|s  
*/ U>w#`Sy[  
package NetFox;
;{EIx*<d  
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1fm4:xHH  
public class TestMethod { NY 756B*  
Atc9[<~WG  
<K;  
public TestMethod() jj_z#6{  
{ ///xx/weblogic60b2_win.exe *`Swv`  
try{ `ltc)$  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); S[JeW  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 3u#bx1  
SiteFileFetch fileFetch = new SiteFileFetch(bean); U$v|c%6  
fileFetch.start(); o}$uP5M8q  
} ^MIF+/bQ  
catch(Exception e){e.printStackTrace ();} fqrQ1{%UH  
?g^42IYG  
fI"sdzu^  
} O2;FaASF  
)12.W=p  
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public static void main(String[] args) JJ_b{ao<  
{ G%^jgr)  
new TestMethod(); ]xC#XYE:dy  
} w\,N}'
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} Su?e\7aj  
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