http断点续传简单实现（java)

/* hU)t5/h;K  
**SiteFileFetch.java fHt\KP  
*/ oqrx7
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package NetFox; V^~RDOSy7n  
import java.io.*; vEv kC  
import java.net.*; m*0YMS>Y |  
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public class SiteFileFetch extends Thread { /\J0)V  
@!ChPl  
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SiteInfoBean siteInfoBean = null; //文件信息Bean Xr*I`BJ  
long[] nStartPos; //开始位置 1v@#b@NXM7  
long[] nEndPos; //结束位置 W/'1ftn?D  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 0cG'37[  
long nFileLength; //文件长度 bWPsfUn#  
boolean bFirst = true; //是否第一次取文件 z4u&#.bU  
boolean bStop = false; //停止标志 <T2O^  
File tmpFile; //文件下载的临时信息 x6ghO-s  
DataOutputStream output; //输出到文件的输出流 j#HXuV6  
}1a}pm2p  
//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 G|i0n   
{ ~id6^#&>  
siteInfoBean = bean; 4,RPidv%O  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); ;QI9OcE@/  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); D 0Xl`0"'  
if(tmpFile.exists ()) p1N}2]e  
{ *&U~Io"U  
bFirst = false; *>fr'jj1$  
read_nPos(); >hunV'vu'  
} +Z`=iia>  
else D(b01EQ;d  
{ r. 82RoG?G  
nStartPos = new long[bean.getNSplitter()]; -L2.cN_  
nEndPos = new long[bean.getNSplitter()]; E'iE#He  
} 3(YvqPp&  
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)
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} r$jWjb  
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public void run() (s8b?Ol/  
{ zJQh~)  
//获得文件长度 OB>Hiy   
//分割文件 S-t#d7'B  
//实例FileSplitterFetch *-VRkS-G  
//启动FileSplitterFetch线程 O'4G'H)   
//等待子线程返回 |)x7qy`  
try{ )JMqC+J3*t  
if(bFirst) k4+vI1Cs  
{ ~IhAO}1  
nFileLength = getFileSize(); 9a`LrB  
if(nFileLength == -1) M/S~"iD  
{ <q63?M
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System.err.println("File Length is not known!"); \gA!)q.;  
} :Cq73:1\B  
else if(nFileLength == -2) NuZ2,<~9  
{ Dfs^W{YA  
System.err.println("File is not access!"); =VC18yA  
} =Rd`"]Mnfb  
else +!lDAkW0  
{ qS?o22  
for(int i=0;i<nStartPos.length;i++) p fc6;K:d  
{ OqtGKda  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ^*.[b  
} ]545:)Q1  
for(int i=0;i<nEndPos.length-1;i++) +\!.X_Ij  
{ %=**cvVy  
nEndPos = nStartPos[i+1]; zlMh^+rMX  
} .n:Q~GEL  
nEndPos[nEndPos.length-1] = nFileLength; rPH7 ]]  
} i>
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} aZ@pfWwa:  
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//启动子线程 B{Q}^Mcxy  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; <rC%$tr  
for(int i=0;i<nStartPos.length;i++) o.
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{ ]4aPn  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), s`yzeo  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), /HIyQW\Ki-  
nStartPos,nEndPos,i); %.Y5%TyP  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 9f~qD&~  
fileSplitterFetch.start(); fPeS;  
} *p/,Z2f  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ^h?fr`  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); @O"7@%nu  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", zgD?e?yPO  
nEndPos = " + nFileLength); Q68~D.V%r  
// fileSplitterFetch[nPos.length-1].start(); L0w6K0J4  
1UP {j`-K|  
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//等待子线程结束 B=A!hXNa  
//int count = 0; w/@ZPBRo]  
//是否结束while循环 n#!c!EfG  
boolean breakWhile = false; }s,NM%oI  
8}n<3_  
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while(!bStop) |5u
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{ KL \>-  
write_nPos(); yD"]:ts3  
Utility.sleep(500); ^4=#,K  
breakWhile = true; rKgl:sj+  
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for(int i=0;i<nStartPos.length;i++) ni;)6,i  
{ n)yDep]$G  
if(!fileSplitterFetch.bDownOver) @]qP:h.  
{ =l(euBb  
breakWhile = false; v3"6'.f;bY  
break; "Enb   
} 4cQP+n  
} KV0*dB;  
if(breakWhile) FJn-cR.n  
break; o~$O$  
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//count++; /8;m.J>bf  
//if(count>4) kk fWiPO^  
// siteStop(); 'TeH(?3G  
} |z)s9B;:#i  
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System.err.println("文件下载结束！"); [8T{=+k  
} Y`~B> J  
catch(Exception e){e.printStackTrace ();} ]I|(/+}M  
} S]3CRJU3`  
]bds~OY5 U  
l"ms:v  
//获得文件长度 fkI 5~Y|  
public long getFileSize() \'~ E%=Q  
{ q7 PCMe  
int nFileLength = -1; ^N7H~CT"  
try{ Pd7\Q]of  
URL url = new URL(siteInfoBean.getSSiteURL()); 8"%Es  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Q6m8N
 
httpConnection.setRequestProperty("User-Agent","NetFox"); q|*^{(tWs  
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int responseCode=httpConnection.getResponseCode(); G&S2U=KdV%  
if(responseCode>=400) L{1sYR%s\  
{ t:2DB)  
processErrorCode(responseCode); $udhTI#,  
return -2; //-2 represent access is error 44KoOY_  
} N3"JouP  
<0d2{RQ;  
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String sHeader; 'K4FS(
q  
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for(int i=1;;i++) =~ Uhr6Q  
{ I|rb"bG  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); SIp)&  
//Utility.log(in.readLine()); u1meysa{0  
sHeader=httpConnection.getHeaderFieldKey(i); VcKB:(:[  
if(sHeader!=null) yzN[%/  
{ 1AAyzAP9`  
if(sHeader.equals("Content-Length")) i#-v4g  
{ \Th<7WbR6#  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); y,5qY}P+  
break; wPg/.N9H  
} /\%<VBx ?q  
} rZ?:$],U!  
else JpS}X\]i  
break; JP4DV=}L  
} 6]v}  
} ~5,^CTAM  
catch(IOException e){e.printStackTrace ();} MZG
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catch(Exception e){e.printStackTrace ();} l5-[a  
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Utility.log(nFileLength); ;M?)-dpZ  
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return nFileLength; G(t:s5:  
} 6qT@M0)i  
Q]9$dr=Kk0  

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//保存下载信息（文件指针位置） 6:5K?Y
o  
private void write_nPos() )R7Sh51P  
{ zamMlmls^  
try{ ~&RTLr#\*M  
output = new DataOutputStream(new FileOutputStream(tmpFile)); -'Z Gc8)  
output.writeInt(nStartPos.length); #I=EYl=Vvi  
for(int i=0;i<nStartPos.length;i++) CNN9a7  
{ sqKx?r72  
// output.writeLong(nPos); wqo:gW_  
output.writeLong(fileSplitterFetch.nStartPos); 2|;|C8C  
output.writeLong(fileSplitterFetch.nEndPos); m?(8T|i  
} [rx9gOOa&  
output.close(); IQJ"B6U)  
} [NSslVr  
catch(IOException e){e.printStackTrace ();} .?{no}u.  
catch(Exception e){e.printStackTrace ();} Z8E<^<|  
} ~kZdep^]  
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*?<N3Rr
*  
//读取保存的下载信息（文件指针位置） x^K4&'</  
private void read_nPos() "'CvB0>  
{ z>PVv)X  
try{ =\6)B{#T  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 1gHe$dzXk  
int nCount = input.readInt(); c~hH 7/v  
nStartPos = new long[nCount]; M|blg!j;  
nEndPos = new long[nCount]; 
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for(int i=0;i<nStartPos.length;i++) v_XN).f;  
{ P}4&J ^  
nStartPos = input.readLong(); .HZd.*  
nEndPos = input.readLong(); h,{Q%sqO  
} | In{5Ek  
input.close(); l\Ozy  
} _*~F1% d  
catch(IOException e){e.printStackTrace ();} G!j9D  
catch(Exception e){e.printStackTrace ();} `4*I1WZW  
} :UdW4
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private void processErrorCode(int nErrorCode) ]q"&V\b  
{ hF$`=hE,F~  
System.err.println("Error Code : " + nErrorCode); 1h@qcom9K_  
} @JGmOwZ  
4vg3F(  
:$D*ab^^P  
//停止文件下载 ehW[LRtq  
public void siteStop() r(r(&NU  
{ 7 z   
bStop = true; }T[@G6#  
for(int i=0;i<nStartPos.length;i++) kx&JY9(&#  
fileSplitterFetch.splitterStop(); 5qrD~D'  
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\=0;EI-j  
} 6La[( )  
} QVjHGY*R  
//负责部分文件的抓取 ^(JrOh'  
**FileSplitterFetch.java Nk9=A4=|  
*/ *5Zow3  
package NetFox; x;[ .ZzQ  
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import java.io.*; 4.,EKw3  
import java.net.*; :-{"9cgFR  
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public class FileSplitterFetch extends Thread { $U[d#:]  
1>e30Ri,g  
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String sURL; //File URL 1]If< <  
long nStartPos; //File Snippet Start Position oEX,\@+u  
long nEndPos; //File Snippet End Position Xy(QK2|  
int nThreadID; //Thread's ID c=u+X` Q  
boolean bDownOver = false; //Downing is over 4$R!)  
boolean bStop = false; //Stop identical 6SCjlaGW5  
FileAccessI fileAccessI = null; //File Access interface |*?N#0s5h  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException &6\&Mcm
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{ `sm Cfh}j6  
this.sURL = sURL; ]\yB,  
this.nStartPos = nStart; I<QUvs%e  
this.nEndPos = nEnd; v:SHaUS  
nThreadID = id; cx:_5GF  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 8fqabR  
} wKpGJ& {  
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public void run() P8c_GEna  
{ QjLU@?&  
while(nStartPos < nEndPos && !bStop) uL)MbM]  
{ im*sSz 0 (  
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try{ a>GA=r  
URL url = new URL(sURL); 3.YH7rN  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); | +;ZC y  
httpConnection.setRequestProperty("User-Agent","NetFox"); DG;u_6;JR  
String sProperty = "bytes="+nStartPos+"-"; :kHk'.V1(  
httpConnection.setRequestProperty("RANGE",sProperty); U
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Utility.log(sProperty); mH,s!6j?Vp  
4>(K~v5;N  
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InputStream input = httpConnection.getInputStream(); Hs)]  
//logResponseHead(httpConnection); r)S:=Is5  
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byte[] b = new byte[1024]; *wJ$U  
int nRead; (~G*'/)  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ai?uJ}  
{ 0c>>:w20D  
nStartPos += fileAccessI.write(b,0,nRead); qtOuA  
//if(nThreadID == 1) ^U~Er'mT  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); E{6ku=2F  
} k?h{6Qd  
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Utility.log("Thread " + nThreadID + " is over!"); wp:$Tqa$  
bDownOver = true; X)SUFhP\  
//nPos = fileAccessI.write (b,0,nRead); eQQVfEvS  
} 8GxT!  
catch(Exception e){e.printStackTrace ();} Oi?Q^ISxP  
} 3R/6/+S-  
} ~^.,Ftkb@7  
{Q/@Y.~<  
08
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//打印回应的头信息 ^I/(9KP#  
public void logResponseHead(HttpURLConnection con) -rsS_[$2  
{ cMi9 Z]  
for(int i=1;;i++) `T[yyOL/  
{ 0(&uH0x  
String header=con.getHeaderFieldKey(i); 5M\0t\uEn  
if(header!=null) Mxz X@GBX  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ,~;`@  
Utility.log(header+" : "+con.getHeaderField(header)); qbnlD\  
else 2;]tItd1  
break; lJa-O  
} _`Kh8G {e  
} ~b8.]Z^  
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public void splitterStop() &/
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{ Uj 3{c  
bStop = true; F4(;O7j9  
} &[\zs&[@y  
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} PvUY Q>Kw  
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/* b<fN,U<k  
**FileAccess.java Ct/6<  
*//文件访问(定位，写) Ql7opl,  
package NetFox; j+<!4 0#  
import java.io.*; 1slt[&4N  
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public class FileAccessI implements Serializable{ 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 0wBr_b!  
RandomAccessFile oSavedFile; ;Xidv9
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long nPos; ,[m4+6G5  
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public FileAccessI() throws IOException KJ?/]oL
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{ TuM
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this("",0); yyR@kOGga  
} Zfu" 8fX  
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public FileAccessI(String sName,long nPos) throws IOException .hvn/5s  
{ QL(}k)dB  
oSavedFile = new RandomAccessFile(sName,"rw"); `).;W
 
this.nPos = nPos; 0tx
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oSavedFile.seek(nPos); >fR#U"KPAB  
} b=Sl`&A  
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public synchronized int write(byte[] b,int nStart,int nLen) BcGQpv&x  
{ /`x|-9  
int n = -1; 7f=9(Zj  
try{ -JF|770i  
oSavedFile.write(b,nStart,nLen); Qzk/oHs  
n = nLen; A[d'*n[  
} ]  )x z  
catch(IOException e) Iq": U  
{ 9aqFdlbY  
e.printStackTrace (); ~?A,GalS  
} cmh/a~vYaY  
#iGz&S3iN$  
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return n; NOmSLIgt7  
} j1toV$)P  
1/qiE{NW  
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} 0H.B>:pv  
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&sA6o"h~  
/* ~pSD|WX  
**SiteInfoBean.java o:Z*F0qm  
*/ .J\U|r  
package NetFox; >-y&k^a=  
<Q-ufF85)  
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public class SiteInfoBean { :S7yM8b`  
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private String sSiteURL; //Site's URL W%Zyt:H`  
private String sFilePath; //Saved File's Path Zk;;~ESOU  
private String sFileName; //Saved File's Name kk5i{.?[  
private int nSplitter; //Count of Splited Downloading File XKU=VOY  
vrW9<{  
k0D&F;a%  
public SiteInfoBean() !xqG-rd '  
{//nSplitter的缺省值为5 kAk,:a;P  
//default value of nSplitter is 5 GrQAho  
this("","","",5); N
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*  
} Mw5!9@Fc7  
E[Io8|QA  
%J%gXk}]  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) v <Ze$^e&  
{ )J88gMk+  
sSiteURL= sURL; RBg
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sFilePath = sPath; izWl5}+'B  
sFileName = sName; 3S2'JOTY  
this.nSplitter = nSpiltter; |]\bgh  
+[}]a3)  
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} 6k3l/~R  
fAUsJ[  
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public String getSSiteURL() K :q-[\G  
{ u#UeJuO  
return sSiteURL; et ~gO!1:*  
} ta6WZu  
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w./EJkKI  
public void setSSiteURL(String value) c`}X2u]k  
{ zXf+ieo  
sSiteURL = value; O}f(h5!k  
} @Q1jH~t  
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public String getSFilePath() ~D=@4(f8|  
{ dO//  
return sFilePath; yEqmB4^-  
} 7ER 2h*  
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}Voh5*$E`  
public void setSFilePath(String value) qL+y8*  
{ (Mm{"J3uv  
sFilePath = value;
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} #f~a\}$I  
d,+n,;6Cf  
jb![
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public String getSFileName() i }gxq  
{ t5Mo'*j =  
return sFileName; K]Cvk%  
} v(7A=/W_  
omA*XXUx=8  
4vQHr!$Ep  
public void setSFileName(String value) Fi/G, [q  
{ |O9=C`G_  
sFileName = value; # |I@`#O  
} 8W[]#~77b  
enzQ}^  
MHYf8HN  
public int getNSplitter() 2,;t%GB  
{ !Cy2>6v7  
return nSplitter; D5m\u$~V  
} VfcQibm  
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public void setNSplitter(int nCount) c-=0l)&'D=  
{ ^Q,/C8qeb  
nSplitter = nCount; *vO'Z &  
} dJ^`9W  
} G0Eq}MyF  
/a|NGh%  
7 f*_  
/* <"+C<[n.  
**Utility.java RM+E  
*/ KRZV9AJ  
package NetFox; U.F65KaKF  
PK4UdT  
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public class Utility { v+sbRuo8  
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public Utility() 7&)F;;H  
{ R*0F)M  
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!v L:P2  
} W8NA.  
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//线程睡眠 =x'%zUgE  
public static void sleep(int nSecond) $bosGG  
{ 9p4U\hx  
try{ ex+AT;o  
Thread.sleep(nSecond); 5Z,lWp2A  
} swFOh5z  
catch(Exception e) ~`E4E  
{ B^?XE(.  
e.printStackTrace (); #+PbcL  
} o{LFXNcg[  
} `C?OAR44  
fO>~V1  
//日志 g:M7/- "  
public static void log(String sMsg) b]#d04]  
{ $@kw>2  
System.err.println(sMsg); F8Wq&X#r  
} 1[`<JCFClc  
c7IR06E  
.A/H+.H;  
public static void log(int sMsg) }2,#[mM  
{ 6S[D"Q94  
System.err.println(sMsg); 3=
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} *KH@u  
} eBIR*TZ):  
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/* U.'@S8  
**TestMethod.java n;`L5  
*/ 5z ^UQq  
package NetFox; 9%14k  
x 4</\o  
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public class TestMethod { 9lJj/  
\=_q{  
ug"<\"  
public TestMethod() H;|:r[d!  
{ ///xx/weblogic60b2_win.exe |uBC0f  
try{ 3og$'#6P  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); a3O_#l-Z  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); _l=  
SiteFileFetch fileFetch = new SiteFileFetch(bean); C}'="g^=sl  
fileFetch.start(); Ef!p:HBJ  
} gdE`UZ\  
catch(Exception e){e.printStackTrace ();} ;S`-9}6  
(x0*(*A}  
lkg*AAR?'  
} Z[S+L"0  
hyfnIb@~}  
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public static void main(String[] args) .{a2z*o  
{ bK8F |  
new TestMethod(); rOb"S*  
} :yjK*"T|OD  
} ZCFf@2&z8  
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